Upload image by NSURLSession

uploadImage.m

/**
 * Generate a mutable URLRequest with authorisation Token (if has) and User-Agent
 *
 * @param url NSURL object
 * @param method GET, POST, PUT or DELETE
 * @return NSMutableURLRequest object, can be modify (add more values) later.
 */
- (NSMutableURLRequest *)requestUrl:(NSURL *)url method:(NSString *)method {
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url
                                                          cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
                                                      timeoutInterval:kRequestTimeOut];
    
    request.HTTPMethod            = method;
    
    /// set request header
    NSString *appMajorVersion    = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleShortVersionString"];
    NSString *appMinorVersion    = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleVersion"];
    NSString *versionString      = [NSString stringWithFormat:@"iOS.%@.%@",appMajorVersion, appMinorVersion];
    [request setValue:versionString forHTTPHeaderField:@"User-Agent"];
    
    // default 'Content-Type'
    [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
    
    return request;
}

- (void)uploadImage:(NSString *)urlString image:(UIImage *)image completion:(void(^)(BOOL succeed))completion {
    NSURL *url               = [NSURL URLWithString:urlString];
    NSMutableURLRequest *req = [self requestUrl:url method:@"POST"];
    NSString *boundary       = [[NSUUID UUID] UUIDString];
    
    // set header
    [req setValue:[NSString stringWithFormat:@"multipart/form-data; boundary=%@", boundary] forHTTPHeaderField:@"Content-Type"];
    
    // filename is xing.jpg - image is convert by UIImageJPEGRepresentation().
    NSMutableData *body = [NSMutableData data];
    [body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[@"Content-Disposition: form-data; name=\"file\"; filename=\"xing.jpg\"\r\n" dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[@"Content-Type: image/jpg\r\n\r\n" dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[NSData dataWithData:UIImageJPEGRepresentation(image, 0.8)]];
    [body appendData:[[NSString stringWithFormat:@"\r\n--%@--\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
    
    NSURLSessionUploadTask *task = [_session uploadTaskWithRequest:req fromData:body completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
        if (completion) {
            dispatch_async(dispatch_get_main_queue(), ^{
                BOOL succeed = [self succeedRequest:(NSHTTPURLResponse *)response error:error];
                completion(succeed);
            });
        }
    }];
    
    [task resume];
    [_tasks addObject:task];
}