上传文件时，我们都的从本地中选择或用相机来拍摄得到文件。

一个上传按钮，单击事件

-(IBAction)btnClick{
   UIActionSheet* actionSheet = [[UIActionSheet alloc]
                                               initWithTitle:@"请选择文件来源"
                                                    delegate:self
                                       cancelButtonTitle:@"取消"
                                destructiveButtonTitle:nil
                                       otherButtonTitles:@"照相机",@"摄像机",@"本地相簿",@"本地视频",nil];
            [actionSheet showInView:self.view];
            [actionSheet release];
}

点击按钮触发的btnClick事件后将会弹出一个如下的选择筐：

接下来将要为UIActionSheet实现其中的委托了。

#pragma mark -
 #pragma UIActionSheet Delegate
 - (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex
 {   
     NSLog(@"buttonIndex = [%d]",buttonIndex);
     switch (buttonIndex) {
         case 0://照相机
             {10                 UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
                 imagePicker.delegate = self;
                 imagePicker.allowsEditing = YES;
                 imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
                 imagePicker.mediaTypes =  [[NSArray alloc] initWithObjects: (NSString *) kUTTypeImage, nil];
                 [self presentModalViewController:imagePicker animated:YES];
                 [imagePicker release];
             }
             break;
         case 1://摄像机
             {22                 UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
                 imagePicker.delegate = self;
                 imagePicker.allowsEditing = YES;
                 imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
                 imagePicker.mediaTypes = [[NSArray alloc] initWithObjects: (NSString *) kUTTypeMovie, nil];
                 imagePicker.videoQuality = UIImagePickerControllerQualityTypeLow;
                 [self presentModalViewController:imagePicker animated:YES];
                 [imagePicker release];
             }
             break;
         case 2://本地相簿
             {35                 UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
                 imagePicker.delegate = self;
                 imagePicker.allowsEditing = YES;
                 imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
                 imagePicker.mediaTypes =  [[NSArray alloc] initWithObjects: (NSString *) kUTTypeImage, nil];
                 [self presentModalViewController:imagePicker animated:YES];
                 [imagePicker release];
             }
             break;
         case 3://本地视频
             {47                 UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
                 imagePicker.delegate = self;
                 imagePicker.allowsEditing = YES;
                 imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
                 imagePicker.mediaTypes =  [[NSArray alloc] initWithObjects: (NSString *) kUTTypeMovie, nil];
                 [self presentModalViewController:imagePicker animated:YES];
                 [imagePicker release];
             }
             break;
         default:
             break;
     }
 }

实现了UIActionSheet的委托后，要发现，我们使用了UIImagePickerController，这个类将帮我们实现选取文件，打开对应的选取方式。比如当ButtonIndex为0的时候，它将帮我们打开照相机，我们可以使用相机拍摄照片作为上传的选取文件。因此，在这里我们还要实现UIImagePickerController的委托：

#pragma mark - 
 #pragma UIImagePickerController Delegate
 - (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
 {
     if ([[info objectForKey:UIImagePickerControllerMediaType] isEqualToString:(NSString*)kUTTypeImage]) {
         UIImage  *img = [info objectForKey:UIImagePickerControllerEditedImage];
         self.fileData = UIImageJPEGRepresentation(img, 1.0);
     } else if ([[info objectForKey:UIImagePickerControllerMediaType] isEqualToString:(NSString*)kUTTypeMovie]) {
         NSString *videoPath = [[info objectForKey:UIImagePickerControllerMediaURL] path];
         self.fileData = [NSData dataWithContentsOfFile:videoPath]; 
     }
     [picker dismissModalViewControllerAnimated:YES];
 }
 
 - (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker 
 {
     [picker dismissModalViewControllerAnimated:YES];
18 }

之后，你选取的文件便保存在了filedata中。就可以随时过来调用了。