iOS開發(fā)中關(guān)于圖片上傳，一般有兩種方法:
1.自己手動寫（如：NSURLMutableRequest等系統(tǒng)類），實現(xiàn)起來比較復雜，暫且不提
2.使用第三方（如：主流的AFNetworking），在開發(fā)中使用第三方比較多，下面就是使用AFN上傳圖片的流程：

//獲取圖片
-(void)avatarTap:(id)sender{
UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"設(shè)置頭像" message:@"" preferredStyle:UIAlertControllerStyleAlert];

//取消
UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {
NSLog(@"The \"Okay/Cancel\" alert's cancel action occured.");
}];

UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
imagePicker.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
imagePicker.allowsEditing = YES;
imagePicker.delegate = self;

//從相冊中選擇
UIAlertAction* fromPhotosAlbumAction = [UIAlertAction actionWithTitle:@"從相冊選擇" style:UIAlertActionStyleDefault  handler:^(UIAlertAction * action) {       
imagePicker.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
[self presentViewController:imagePicker animated:YES completion:nil];
}];

//從圖庫選擇
UIAlertAction* fromPhotoAction = [UIAlertAction actionWithTitle:@"從圖庫選擇" style:UIAlertActionStyleDefault  handler:^(UIAlertAction * action) {                              
imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
[self presentViewController:imagePicker animated:YES completion:nil];
}];

//相機拍攝
UIAlertAction* fromCameraAction = [UIAlertAction actionWithTitle:@"相機拍攝" style:UIAlertActionStyleDefault  handler:^(UIAlertAction * action) {
if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]){
UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
[self presentViewController:imagePicker animated:YES completion:nil]; }
}];

[alertController addAction:cancelAction];
[alertController addAction:fromCameraAction];
[alertController addAction:fromPhotoAction];
[alertController addAction:fromPhotosAlbumAction];
[self presentViewController:alertController animated:YES completion:nil];
}

//如何進行壓縮
//將圖片尺寸改為240x240
UIImage *smallImage=[self scaleFromImage:image toSize:CGSizeMake(240.0f, 240.0f)];
//寫入jpg文件
[UIImageJPEGRepresentation(smallImage, 1.0f) writeToFile:imageFilePath atomically:YES];

//+ (UIImage *)imageWithCGImage:(CGImageRef)cgImage scale:(CGFloat)scale orientation:(UIImageOrientation)orientation NS_AVAILABLE_IOS(4_0);**
//該方法使用一個CGImageRef創(chuàng)建UIImage，在創(chuàng)建時還可以指定放大倍數(shù)以及旋轉(zhuǎn)方向。當scale設(shè)置為1的時候，新創(chuàng)建的圖像將和原圖像尺寸一摸一樣，而orientaion則可以指定新的圖像的繪制方向。
//也可以用這個方法進行壓縮你會發(fā)現(xiàn)得到的大小會小了很多倍，如果想測試的話可以轉(zhuǎn)換成 NSData 打印一下。

//獲取壓縮后的圖片
+ (UIImage *) scaleFromImage: (UIImage *) imagetoSize: (CGSize)size{
UIGraphicsBeginImageContext(size);
[image drawInRect:CGRectMake(0, 0, size.width, size.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}

#pragma mark - 圖片上傳
//上傳圖片(單張)
+(void)uploadPhotoAndController:(UIViewController *)controller WithSize:(CGSize)size Image:(UIImage*)image AndFinish:(void (^)(NSDictionary *, NSError *))finish
{
    //加載提示菊花
    MBProgressHUD *hud;
    if(controller){
        hud = [MBProgressHUD showHUDAddedTo:controller.view animated:YES];
        hud.label.text = NSLocalizedString(@"加載中...", @"HUD loading title");
    }
    
    //1. 存放圖片的服務器地址，這里我用的宏定義
    NSString * url = [NSString stringWithFormat:@"%@%@",Hx_Main_heard_API,IMAGE_UPLOAD_URL_API];
    
    //2. 利用時間戳當做圖片名字
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    formatter.dateFormat = @"yyyyMMddHHmmss";
    NSString *imageName = [formatter stringFromDate:[NSDate date]];
    NSString *fileName = [NSString stringWithFormat:@"%@.jpg",imageName];
    
    //3. 圖片二進制文件
    NSData *imageData = UIImageJPEGRepresentation(image, 0.7f);
    NSLog(@"upload image size: %ld k", (long)(imageData.length / 1024));
    
    //4. 發(fā)起網(wǎng)絡(luò)請求
    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
    manager.requestSerializer = [AFHTTPRequestSerializer serializer];
    manager.responseSerializer = [AFJSONResponseSerializer serializer];
    [manager POST:url parameters:nil constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {
        // 上傳圖片，以文件流的格式，這里注意：name是指服務器端的文件夾名字
        [formData appendPartWithFileData:imageData name:@"file" fileName:fileName mimeType:@"image/jpeg"];
    } success:^(AFHTTPRequestOperation *operation, id responseObject) {
        //上傳成功時的回調(diào)
        [hud hideAnimated:YES];
        NSLog(@"%@",responseObject);
        finish(responseObject,nil);
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        //失敗時的回調(diào)
        [hud hideAnimated:YES];
        finish(nil,error);
    }];
}


// 上傳圖片（多張）
+(void)uploadPhotoAndController:(UIViewController *)controller WithSize:(CGSize)size Image:(UIImage*)image AndFinish:(void (^)(NSDictionary *, NSError *))finish
{
    //加載提示菊花
    MBProgressHUD *hud;
    if(controller){
        hud = [MBProgressHUD showHUDAddedTo:controller.view animated:YES];
        hud.label.text = NSLocalizedString(@"加載中...", @"HUD loading title");
    }
    
    //1. 存放圖片的服務器地址，這里我用的宏定義
    NSString * url = [NSString stringWithFormat:@"%@%@",Hx_Main_heard_API,IMAGE_UPLOAD_URL_API];
    
    //2. 發(fā)起網(wǎng)絡(luò)請求
    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
    manager.requestSerializer = [AFHTTPRequestSerializer serializer];
    manager.responseSerializer = [AFJSONResponseSerializer serializer];
    [manager POST:url parameters:nil constructingBodyWithBlock:^(id<AFMultipartFormData> formData)
     {
         // 上傳多張圖片
         for(NSInteger i = 0; i < self.imageDataArray.count; i++)
         {
             //取出單張圖片二進制數(shù)據(jù)
             NSData * imageData = self.imageDataArray[i];
             
             // 上傳的參數(shù)名，在服務器端保存文件的文件夾名
             NSString * Name = [NSString stringWithFormat:@"%@%ld", Image_Name, i+1];
             // 上傳filename
             NSString * fileName = [NSString stringWithFormat:@"%@.jpg", Name];
             
             [formData appendPartWithFileData:imageData name:Name fileName:fileName mimeType:@"image/jpeg"];
         }
     }
          success:^(AFHTTPRequestOperation *operation, id responseObject)
     {
         //上傳成功時的回調(diào)
         [hud hideAnimated:YES];
         NSLog(@"%@",responseObject);
         finish(responseObject,nil);
     }
          failure:^(AFHTTPRequestOperation *operation, NSError *error)
     {
         //失敗時的回調(diào)
         [hud hideAnimated:YES];
         finish(nil,error);
     }];
}