网络底层 - 符琼林的个人博客

三次握手-四次挥手

http 的传输过程
- 域名-> ip
- http tcp 三次握手
- 传head数据
- 传一段空行
- 传body数据
Server封装 head+body
- 传head
- 传空行
- 传body
- 断开连接四次挥手

三次握手

SYN：同步序列编号（Synchronize Sequence Numbers）。 Client将标志位SYN置为1，随机产生一个值seq=J 该序列编号为TCP连接初始端(一般是客户端)的初始序列编号。在这里，可以把TCP序列编号看作是一个范围从0到4，294，967，295的32位计数器。通过TCP连接交换的数据中每一个字节都经过序列编号。在TCP报头中的序列编号栏包括了TCP分段中第一个字节的序列编号。
ACK：确认标志,确认编号(Acknowledgement Number)栏有效。大多数情况下该标志位是置位的。TCP报头内的确认编号栏内包含的确认编号(w+1，Figure-1)为下一个预期的序列编号，同时提示远端系统已经成功接收所有数据。

四次挥手

ip头TCP-UDP头

ip表头，通常20个字节
TCP表，保证可靠性
32位序号
UDP，不可靠
分片处理

断点续传

#import <Foundation/Foundation.h>
#import "KCDownloadNetwork.h"

typedef void (^KCRequestHandleBlock)(id result,NSString* msg, NSInteger errorCode);

@interface KCNetwork : NSObject

+ (instancetype)shared;

- (NSURLSessionDataTask *)post:(NSString*)url token:(NSString*)token reqData:(NSDictionary*)params handle:(KCRequestHandleBlock)handleblock;

@end

#import "KCNetwork.h"

@interface KCNetwork()

@property (nonatomic, copy) KCRequestHandleBlock handleBlock;
@property (nonatomic, strong) NSMutableData *receivedData;

@end

@implementation KCNetwork

+ (instancetype)shared{
    static KCNetwork *network;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        network = [[KCNetwork alloc] init];
    });
    return network;
}


- (NSURLSessionDataTask *)post:(NSString*)url token:(NSString*)token reqData:(NSDictionary*)params handle:(KCRequestHandleBlock)handleblock{
    
    // 校验url
    if (!url || url.length == 0) {
        NSLog(@"url 无效!");
        return nil;
    }
    // token
    if (!token || token.length == 0) {
        NSLog(@"token 无效!");
        return nil;
    }
    
    // 记录回调,在任何你想要操作的地方,随时拿出来
    self.handleBlock = handleblock;
    
    // 操作URL
    NSURL *requestUrl = [NSURL URLWithString:url];
    // 定义request 来设定请求头 -- afn  resquestSerizetion nsset
    // https + ssl cer  token client
    // URL :  GET
    // post : 请求体
    // httpbody --- httpStream afn
    
    NSMutableURLRequest *mRequest = [NSMutableURLRequest requestWithURL:requestUrl];
    [mRequest setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
    [mRequest setValue:token forHTTPHeaderField:@"token"];
    // 请求方法
    mRequest.HTTPMethod = @"POST";
    /**
     别回答 参数在url 后面拼接了:
     post get 根本区别: 数据保存的 head VS body
     */
    // 默认60秒
    mRequest.timeoutInterval = 30.0;
    
    // 请求体处理
    mRequest.HTTPBody = [[self convertToJSONData:params] dataUsingEncoding:NSUTF8StringEncoding];
    
    NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]
                                                          delegate:self
                                                     delegateQueue:[NSOperationQueue mainQueue]];
    
    // session --> task : id
    //创建请求 Task 该次请求的指针 句柄 *p  dataTask
    NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:mRequest];
    
    [dataTask resume];
    
    return dataTask;
    
}

#pragma mark -- NSURLSessionDataDelegate

// 1.接收到服务器的响应
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition))completionHandler {
    
    completionHandler(NSURLSessionResponseAllow);
}

// 返回body 多次返回 为什么 MTU限制  TCP 包按照顺序返回
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data {
    
    [self.receivedData appendData:data];
    
}

// 任务完成时调用或者失败
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error {
    
    if(error == nil){
        NSString* jsonString =  [[NSString alloc] initWithData:self.receivedData  encoding:NSUTF8StringEncoding];
        id obj = [self dictionaryWithJsonString:jsonString];
        NSLog(@"%@",obj);
        self.handleBlock(obj, @"请求成功", 200);
    }else{
        self.handleBlock(nil,[self getErrCode:error.code],error.code);
    }
}



#pragma mark - 错误代码

-(NSString*)getErrCode:(NSInteger)code{
    
    switch (code) {
        case 700:
            return @"会话过期";
            break;
            
        case 800:
            return @"后台gg正常维护中";
            break;
            
        case 404:
            return @"网络连接失败";
            break;
            
        case 500:
            return @"服务器拒绝请求";
            break;
            
        default:
            break;
    }
    
    return @"未知错误";
}

// json
#pragma mark - json 序列化
- (NSString*)convertToJSONData:(id)infoDict{
    NSError *error;
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:infoDict
                                                       options:NSJSONWritingPrettyPrinted
                                                         error:&error];
    NSString *jsonString = @"";
    if (!jsonData){
        NSLog(@"json 序列化错误: %@", error);
    }else{
        jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
    }
    
    jsonString = [jsonString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
    //去除掉首尾的空白字符和换行字符
    [jsonString stringByReplacingOccurrencesOfString:@"\n" withString:@""];
    return jsonString;
}

#pragma mark - json 反序列化 -- json 解析
-(NSDictionary *)dictionaryWithJsonString:(NSString *)jsonString
{
    if (jsonString == nil) {
        return nil;
    }
    NSData *jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
    NSError *err;
    NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:jsonData
                                                        options:NSJSONReadingMutableContainers
                                                          error:&err];
    if(err){
        NSLog(@"json解析失败：%@",err);
        return nil;
    }
    return dic;
}

#pragma mark - lazy

- (NSMutableData *)receivedData{
    if (!_receivedData) {
        _receivedData = [NSMutableData data];
    }
    return _receivedData;
}

@end

#import <Foundation/Foundation.h>

@protocol KCDownLoadDelegate 
@optional
- (void)backDownprogress:(float)progress tag:(NSInteger)tag;
- (void)downSucceed:(NSURL*)url tag:(NSInteger)tag;
- (void)downError:(NSError*)error tag:(NSInteger)tag;
@end
  
@interface KCDownloadNetwork : NSObject

@property (nonatomic, strong) NSURLSession* session;
@property (nonatomic, strong) NSURLSessionDownloadTask* downloadTask;
@property (nonatomic, strong) NSData* resumeData;
@property (nonatomic, weak) id myDeleate;
@property (nonatomic, assign) NSInteger tag;//某个文件下载的的标记

-(void)downFile:(NSString*)fileUrl isBreakpoint:(BOOL)breakpoint;

//暂停 继续 取消 文件下载
-(void)suspendDownload;
-(void)cancelDownload;

@end

#import "KCDownloadNetwork.h"
#import <CommonCrypto/CommonDigest.h>


@interface KCDownloadNetwork()
@property (nonatomic) BOOL  mIsSuspend;
@property (nonatomic, copy) NSString* fileName;
@property (nonatomic, strong) NSData *myResumeData;

@end

@implementation KCDownloadNetwork

- (void)downFile:(NSString*)fileUrl isBreakpoint:(BOOL)breakpoint{
    
    if (!fileUrl || fileUrl.length == 0 || ![self checkIsUrlAtString:fileUrl]) {
        NSLog(@"fileUrl 无效");
        return ;
    }
    
//    // 判断之前是否存在
//    // 这个地方是不是可以写成唯一的地址
//    if ([[NSFileManager defaultManager] fileExistsAtPath:[self getTmpFileUrl]]) {
//        [self downloadWithResumeData];
//        return;
//    }
    
    NSURL *url = [NSURL URLWithString:fileUrl];

    if (!self.session) {
        
        //0.MD5 加密
        self.fileName = [self md5:fileUrl];
        
        //1.创建NSURLSession,设置代理
        NSURLSessionConfiguration *config = [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:[self currentDateStr]];
        // 允许蜂窝网络: 你可以做偏好设置
        config.allowsCellularAccess = YES;
        config.timeoutIntervalForRequest = 30;
        //创建一个下载线程
        self.session = [NSURLSession sessionWithConfiguration:config
                                                     delegate:self
                                                delegateQueue:[NSOperationQueue mainQueue]];
    }

    //2.创建task 请求句柄
    if(breakpoint == NO){
        self.downloadTask = [self.session downloadTaskWithURL:url];
    }else{
        // 断点续传
        [self downloadWithResumeData];
    }
    
    [self.downloadTask resume];
    
    [self saveTmpFile];
    
}


#pragma mark - NSURLSessionDelegate
//每次传一个包 调用一次该函数 512M
-(void)URLSession:(nonnull NSURLSession *)session downloadTask:(nonnull NSURLSessionDownloadTask *)downloadTask didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWritten totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite{

    float dowProgeress = 1.0 * totalBytesWritten / totalBytesExpectedToWrite;
    if (self.myDeleate && [self.myDeleate respondsToSelector:@selector(backDownprogress:tag:)]) {
        [self.myDeleate backDownprogress:dowProgeress tag:self.tag];
    }
    
}
/*
 2.下载完成之后调用该方法
 */
-(void)URLSession:(nonnull NSURLSession *)session downloadTask:(nonnull NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(nonnull NSURL *)location{

    NSLog(@"location == %@",location.path);
    
    //拼接Doc 更换的路径
    NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES) lastObject];
    NSString *file = [documentsPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.mp4",self.fileName]];
    
    //创建文件管理器
    NSFileManager *manager = [NSFileManager defaultManager];
    if ([manager fileExistsAtPath: file]) {
        //如果文件夹下有同名文件  则将其删除
        [manager removeItemAtPath:file error:nil];
    }
    NSError *saveError;
    [manager moveItemAtURL:location toURL:[NSURL URLWithString:file] error:&saveError];
    
    //将视频资源从原有路径移动到自己指定的路径
    BOOL success = [manager copyItemAtPath:location.path toPath:file error:nil];
    if (success) {
        dispatch_async(dispatch_get_main_queue(), ^{
            NSURL *url = [[NSURL alloc]initFileURLWithPath:file];
            if(self.myDeleate && [self.myDeleate respondsToSelector:@selector(downSucceed:tag:)])
                [self.myDeleate downSucceed:url tag:self.tag];
        });
    }
    //已经拷贝 删除缓存文件
    [manager removeItemAtPath:location.path error:nil];
    
    [manager removeItemAtPath:[self getTmpFileUrl] error:nil];
}

//下载失败调用
-(void)URLSession:(nonnull NSURLSession *)session task:(nonnull NSURLSessionTask *)task didCompleteWithError:(nullable NSError *)error{
    
    if(error && self.myDeleate && [self.myDeleate respondsToSelector:@selector(downError:tag:)] && error.code != -999)
        [self.myDeleate downError:error tag:self.tag];
}

- (void)URLSessionDidFinishEventsForBackgroundURLSession:(NSURLSession *)session{
    NSLog(@"所有后台任务已经完成: %@",session.configuration.identifier);
    
}
    


#pragma mark - private

//暂停下载
-(void)suspendDownload{
 
    if (self.mIsSuspend) {
        [self.downloadTask resume];
    }else{
        [self.downloadTask suspend];
    }
    self.mIsSuspend = !self.mIsSuspend;
}


//取消下载
-(void)cancelDownload{
    
//    [self.downloadTask cancel];
    __weak typeof(self) weakSelf = self;
    [self.downloadTask cancelByProducingResumeData:^(NSData * _Nullable resumeData) {
       
//        weakSelf.resumeData = resumeData;
        weakSelf.downloadTask  = nil;
        [resumeData writeToFile:[weakSelf getTmpFileUrl] atomically:NO];
    }];
    
    
}

//断点下载
-(void)downloadWithResumeData{

    if (!self.session) {
        return;
    }
    
    NSData *data = nil;
    
    if (self.resumeData) {
        data = self.resumeData;
    }else{
        
        NSFileManager *fm = [NSFileManager defaultManager];
        NSData *datas     = [fm contentsAtPath:[self getTmpFileUrl]];
        NSString *fileStr = [[NSString alloc] initWithData:datas encoding:NSUTF8StringEncoding];
        
        NSLog(@"%@----%@",[self getTmpFileUrl],fileStr);
        data = datas;
    }
    
    self.downloadTask = [self.session downloadTaskWithResumeData:data];
}

//未下载完的临时文件url地址
-(NSString*)getTmpFileUrl{
    
    NSString *docPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
    NSString *filePath = [docPath stringByAppendingPathComponent:@"download.tmp"];
    NSLog(@"%@",filePath);
    
//    NSString* url = [NSString stringWithFormat:@"/Users/LM/Desktop/%@.tmp",self.fileName];
    return filePath;
}

//提前保存临时文件 预防下载中杀掉app
//开启定时器
-(void)saveTmpFile{
    
    [NSTimer scheduledTimerWithTimeInterval:4 repeats:YES block:^(NSTimer * _Nonnull timer) {
       
        [self downloadTmpFile];
    }];

}

//杀掉app后 不至于下载的部分文件全部丢失，死亡处理
- (void)downloadTmpFile{
    __weak typeof(self) weakSelf = self;
    [self.downloadTask cancelByProducingResumeData:^(NSData * _Nullable resumeData) {
        //先保存
        weakSelf.resumeData = resumeData;
        weakSelf.downloadTask  = nil;
        [resumeData writeToFile:[weakSelf getTmpFileUrl] atomically:NO];
        //在下载
        self.downloadTask =  [self.session downloadTaskWithResumeData:resumeData];
        [self.downloadTask resume];
    }];

    
}

//用url获取文件名称 MD5加密
- (NSString *)md5:(NSString *)string{
    const char *cStr = [string UTF8String];
    unsigned char digest[CC_MD5_DIGEST_LENGTH];
    
    CC_MD5(cStr, (CC_LONG)strlen(cStr), digest);
    
    NSMutableString *result = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH * 2];
    for (int i = 0; i < CC_MD5_DIGEST_LENGTH; i++) {
        [result appendFormat:@"%02X", digest[i]];
    }
    
    return result;
}

//获取当前时间 下载id标识用
- (NSString *)currentDateStr{
    NSDate *currentDate = [NSDate date];//获取当前时间，日期
    NSTimeInterval timeInterval = [currentDate timeIntervalSince1970];
    return [NSString stringWithFormat:@"%.f",timeInterval];
}

- (BOOL)checkIsUrlAtString:(NSString *)url {
    NSString *pattern = @"http(s)?://([\\w-]+\\.)+[\\w-]+(/[\\w- ./?%&=]*)?";
    
    NSRegularExpression *regex = [[NSRegularExpression alloc] initWithPattern:pattern options:0 error:nil];
    NSArray *regexArray = [regex matchesInString:url options:0 range:NSMakeRange(0, url.length)];
    
    if (regexArray.count > 0) {
        return YES;
    }else {
        return NO;
    }
}

- (void)dealloc
{
    [self.session invalidateAndCancel];
    self.session = nil;
    [self.downloadTask cancel];
    self.downloadTask = nil;
}
@end

#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>
#import <AVKit/AVKit.h>
#import "KCNetwork.h"

@interface ViewController ()

@property (weak, nonatomic) IBOutlet UIProgressView *progress;
@property (weak, nonatomic) IBOutlet UILabel *lab1;
@property (weak, nonatomic) IBOutlet UILabel *lab2;
@property (weak, nonatomic) IBOutlet UILabel *msgLab;

@property (weak, nonatomic) IBOutlet UILabel *proLab;

@property (nonatomic, strong) KCDownloadNetwork *fileDownloadNetwork;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (IBAction)btnClick:(id)sender {
    
//    NSString *url = @"http://127.0.0.1:8080/static/123.mp4";
    NSString *url = @"http://m.lanlingfuli.com/aif/home/getRecomm";
    NSString *token = @"23134543223";
    NSDictionary *para = @{@"agency":@"ios",@"pageIndex":@"1"};

    // NSURLSession  --->  task  --->  id
    // tag  ---  indextify
    
    [[KCNetwork shared] post:url token:token reqData:para handle:^(id result, NSString *msg, NSInteger errorCode) {
        NSLog(@"%@",[NSThread currentThread]);
        if (errorCode == 200) {
            NSLog(@"result == %@",result);
        }else{
            
        }
    }];
    
    
}


//------------------------------大文件下载---------------------------------

// 开始下载
- (IBAction)startDown:(id)sender {
    [self downFile:NO];
}

// 断点续传
- (IBAction)breakpointContinuingly:(id)sender {
    [self downFile:YES];
}


-(void)downFile:(BOOL)breakpoint{
    
    //172.16.127.104
    NSString *fileUrl = @"https://pic.ibaotu.com/00/48/71/79a888piCk9g.mp4";

    
    if(self.fileDownloadNetwork == nil){
        self.fileDownloadNetwork = [KCDownloadNetwork new];
        self.fileDownloadNetwork.tag = 1; // 区别 不同的任务下载类型
        self.fileDownloadNetwork.myDeleate = self;
        //第二个参数 需要重新下载还是接着上次的下载
    }
    
    // 第一次 : 没有文件
    // 断点  :  临时文件
    [self.fileDownloadNetwork downFile:fileUrl isBreakpoint:breakpoint];

}

//暂停下载
- (IBAction)suspendedDown:(id)sender {
    [self.fileDownloadNetwork suspendDownload];
}
//取消下载
- (IBAction)cancelDown:(id)sender {
    [self.fileDownloadNetwork cancelDownload];
}



//进度返回   每一个数据包回来调用一次
- (void)backDownprogress:(float)progress tag:(NSInteger)tag{
    
    self.progress.progress = progress;
    self.proLab.text = [NSString stringWithFormat:@"%0.1f%@",progress*100,@"%"];
}

//下载成功
- (void)downSucceed:(NSURL*)url tag:(NSInteger)tag{
    NSLog(@"下载成功,准备播放");
    [self paly: url];
    self.progress.progress = 0;
    self.proLab.text = @"0.0%";
    self.fileDownloadNetwork = nil;
}

//下载失败
- (void)downError:(NSError*)error tag:(NSInteger)tag{
    
    self.fileDownloadNetwork = nil;
    self.progress.progress = 0;
    self.proLab.text = @"0.0%";
    NSLog(@"下载失败,请再次下载 :%@",error);
}



//传入本地url 进行视频播放
-(void)paly:(NSURL*)playUrl{
    
    //系统的视频播放器
    AVPlayerViewController *controller = [[AVPlayerViewController alloc]init];
    //播放器的播放类
    AVPlayer * player = [[AVPlayer alloc]initWithURL:playUrl];
    controller.player = player;
    //自动开始播放
    [controller.player play];
    //推出视屏播放器
    [self  presentViewController:controller animated:YES completion:nil];
}

@end

#import "AppDelegate.h"

@interface AppDelegate ()
@property (nonatomic, copy) NSString *identifier;
@end

@implementation AppDelegate

- (void)application:(UIApplication *)application handleEventsForBackgroundURLSession:(NSString *)identifier completionHandler:(void (^)(void))completionHandler{
    self.identifier = identifier;
}

- (void)applicationWillEnterForeground:(UIApplication *)application {
    // Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
    NSLog(@"已经下载好了: %@",self.identifier);

}

- (void)applicationWillTerminate:(UIApplication *)application {
    // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
    NSLog(@"程序被杀死，applicationWillTerminate");
}
@end

#### 文件流处理
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

typedef void (^KCFileHandleBlock)(NSURL* fileUrl, NSString *progress);

@interface KCFileStreamNetwork : NSObject

- (NSURLSessionDataTask*)getDownFileUrl:(NSString*)fileUrl backBlock:(KCFileHandleBlock)handleBlock;
@property(nonatomic,strong)UILabel *proLab;

@end

#import "KCFileStreamNetwork.h"

@interface KCFileStreamNetwork()
@property (nonatomic, copy) KCFileHandleBlock handleBlock;
@property (nonatomic, copy) NSString *mFileUrl;
@property (nonatomic, strong) NSMutableData *receiveData;
@property (nonatomic, strong) NSOutputStream *outpustream;
@property (nonatomic, strong) NSFileHandle *fileHandle;
@end

@implementation KCFileStreamNetwork

- (instancetype)init {
    
    if(self=[super init]){
        _receiveData = [[NSMutableData alloc] init];
        return self;
    }
    return nil;
}

- (NSURLSessionDataTask*)getDownFileUrl:(NSString*)fileUrl backBlock:(KCFileHandleBlock)handleBlock{
    
    if(fileUrl==nil || handleBlock==nil)  return nil;
    
    self.handleBlock = handleBlock;
    //确定请求路径
    NSURL *url0 = [NSURL URLWithString:fileUrl];
    //创建可变请求对象
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url0];
    request.HTTPMethod = @"GET";
    request.timeoutInterval = 30.0;
    
    NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]
                                                          delegate:self
                                                     delegateQueue:[NSOperationQueue   mainQueue]];
    
    NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request];
    //发送请求
    [dataTask resume];
    
    return dataTask;
    
}


NSInteger fileDownPro = 0;
NSInteger fileTotalPro = 0;
#pragma mark -- NSURLSessionDataDelegate// 1.接收到服务器的响应
//接受的http的 head数据
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition))completionHandler {
    
    fileTotalPro = response.expectedContentLength;//字节
    completionHandler(NSURLSessionResponseAllow);
}

// 2.接收到http 的body数据
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data {
    
    //这样会造成内存暴增
    //[self.receiveData appendData:data];
    
    //创建流，append为YES的话，每次写入都是追加到文件尾部
    self.outpustream = [NSOutputStream outputStreamToFileAtPath:[self getSaveFilePath] append:YES];

    //一点一点的存 细水流长
    dispatch_async(dispatch_get_global_queue(0, 0), ^{
//        [self saveFile:data];
        [self.outpustream open];
        [self.outpustream write:data.bytes maxLength:data.length];
        [self.outpustream close];
    });
    
    fileDownPro  = fileDownPro +  data.length;
    float downPro = fileDownPro/(fileTotalPro*1.0)*100;
    NSString *progress = [NSString stringWithFormat:@"%.2f%@",downPro,@"%"];
    self.handleBlock(nil, progress);
}

// 3.3.任务完成时调用
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error {
    
    NSLog(@"下载完成");
    
    if (!error) {
//        [self.receiveData writeToFile:[self getSaveFilePath] atomically:YES];
    }
}

- (void)saveFile:(NSData *)data {
    //保存文件的路径
    NSString *filePath = [self getSaveFilePath];
    //如果文件不存在，返回的是nil
    NSFileHandle *fileHandle = [NSFileHandle fileHandleForWritingAtPath:filePath];
    //判断文件存不存在
    if (fileHandle == nil) {
        //如果文件不存在，会自动创建
        [data writeToFile:filePath atomically:YES];
    }else {
        //让offset指向文件的末尾
        [fileHandle seekToEndOfFile];
        //在文件的末尾再继续写入文件
        [fileHandle writeData:data];
        // 同步一下防止操作混乱
        [fileHandle synchronizeFile];
        //关闭文件
        [fileHandle closeFile];
    }
}

- (NSString *)getSaveFilePath{
    
    NSString *filePath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"video.mp4"];
    if (![[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
        [[NSFileManager defaultManager] createFileAtPath:filePath contents:nil attributes:nil];
    }
    return filePath;
}
@end

#import "ViewController.h"
#import "KCFileStreamNetwork.h"

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UILabel *progressLabel;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}


//文件流下载
- (IBAction)fileSteamBtn:(id)sender {
    
    __weak typeof(self) weakSelf = self;
    
    KCFileStreamNetwork *fileStream = [KCFileStreamNetwork new];
    [fileStream  getDownFileUrl:@"https://pic.ibaotu.com/00/48/71/79a888piCk9g.mp4" backBlock:^(NSURL *fileUrl,NSString *progress) {
        weakSelf.progressLabel.text = progress;
        if (fileUrl) {
            NSLog(@"文件路径:%@",[fileUrl absoluteString]);
        }
    }];
    
}

- (IBAction)editFileBtn:(id)sender {
    
    NSString* filePath =  @"/Users/LM/Desktop/data.txt";
    NSFileManager* fm = [NSFileManager defaultManager];
    NSData* fileData =  [fm contentsAtPath:filePath];
    
    NSFileHandle *fielHandle = [NSFileHandle fileHandleForUpdatingAtPath:filePath];
    //[fielHandle seekToFileOffset:2];
    [fielHandle seekToEndOfFile];
    NSString *str = @"你好";
    NSData* stringData = [str dataUsingEncoding:NSUTF8StringEncoding];
    
    [fielHandle writeData:stringData];
    [fielHandle closeFile];
    
}
@end

网络抓包

请求格式

#import "KCNetwork.h"

typedef void (^KCRequestHandleBlock)(id result,NSString* msg, NSInteger errorCode);

@interface KCNetwork()

@property (nonatomic, copy) KCRequestHandleBlock handleBlock;
@property (nonatomic, strong) NSMutableData *receivedData;

@end

@implementation KCNetwork

+ (instancetype)shared{
    static KCNetwork *network;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        network = [[KCNetwork alloc] init];
    });
    return network;
}


- (NSURLSessionDataTask *)post:(NSString*)url token:(NSString*)token reqData:(NSDictionary*)params handle:(KCRequestHandleBlock)handleblock{
    
    // 校验url
    if (!url || url.length == 0) {
        NSLog(@"url 无效!");
        return nil;
    }
    // token
    if (!token || token.length == 0) {
        NSLog(@"token 无效!");
        return nil;
    }
    // 记录回调,在任何你想要操作的地方,随时拿出来
    self.handleBlock = handleblock;
    
    // 操作URL
    NSURL *requestUrl = [NSURL URLWithString:url];
    // 定义request 来设定请求头
    NSMutableURLRequest *mRequest = [NSMutableURLRequest requestWithURL:requestUrl];
    [mRequest setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
    [mRequest setValue:token forHTTPHeaderField:@"token"];
    // 请求方法
    mRequest.HTTPMethod = @"POST";
    /**
     别回答 参数在url 后面拼接了:
     post get 根本区别: 数据保存的 head VS body
     */
    // 默认60秒
    mRequest.timeoutInterval = 30.0;
    
    // 请求体处理
    mRequest.HTTPBody = [[self convertToJSONData:params] dataUsingEncoding:NSUTF8StringEncoding];
    
    NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]
                                                          delegate:self
                                                     delegateQueue:[NSOperationQueue mainQueue]];
    
    //创建请求 Task 该次请求的指针 句柄 *p  dataTask
    NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:mRequest];
    
    [dataTask resume];
    
    return dataTask;
    
}

#pragma mark -- NSURLSessionDataDelegate

// 1.接收到服务器的响应
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition))completionHandler {
    
    completionHandler(NSURLSessionResponseAllow);
}

// 返回body 多次返回 为什么 MTU限制  TCP 包按照顺序返回
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data {
    
    [self.receivedData appendData:data];
    
}

// 任务完成时调用或者失败
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error {
    
    if(error == nil){
        NSString* jsonString =  [[NSString alloc] initWithData:self.receivedData  encoding:NSUTF8StringEncoding];
        id obj = [self dictionaryWithJsonString:jsonString];
        NSLog(@"%@",obj);
        self.handleBlock(obj, @"请求成功", 200);
    }else{
        self.handleBlock(nil,[self getErrCode:error.code],error.code);
    }
}



#pragma mark - 错误代码

-(NSString*)getErrCode:(NSInteger)code{
    
    switch (code) {
        case 700:
            return @"会话过期";
            break;
            
        case 800:
            return @"后台gg正常维护中";
            break;
            
        case 404:
            return @"网络连接失败";
            break;
            
        case 500:
            return @"服务器拒绝请求";
            break;
            
        default:
            break;
    }
    
    return @"未知错误";
}

#pragma mark - json 序列化
- (NSString*)convertToJSONData:(id)infoDict{
    NSError *error;
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:infoDict
                                                       options:NSJSONWritingPrettyPrinted
                                                         error:&error];
    NSString *jsonString = @"";
    if (!jsonData){
        NSLog(@"json 序列化错误: %@", error);
    }else{
        jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
    }
    
    jsonString = [jsonString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
    //去除掉首尾的空白字符和换行字符
    [jsonString stringByReplacingOccurrencesOfString:@"\n" withString:@""];
    return jsonString;
}

#pragma mark - json 反序列化 -- json 解析
-(NSDictionary *)dictionaryWithJsonString:(NSString *)jsonString
{
    if (jsonString == nil) {
        return nil;
    }
    NSData *jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
    NSError *err;
    NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:jsonData
                                                        options:NSJSONReadingMutableContainers
                                                          error:&err];
    if(err){
        NSLog(@"json解析失败：%@",err);
        return nil;
    }
    return dic;
}

#pragma mark - lazy

- (NSMutableData *)receivedData{
    if (!_receivedData) {
        _receivedData = [NSMutableData data];
    }
    return _receivedData;
}
@end