Question

我有一个简单的iPhone应用程序我显示一个UIImagePicker，让用户选择一个图像然后我在图像上执行一些代码，并希望此代码在解除UIImagePicker后执行。

编辑：更新了代码，问题仍然存在：

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info { NSData* data = UIImagePNGRepresentation([info objectForKey:@"UIImagePickerControllerOriginalImage"]); [[picker parentViewController] dismissModalViewControllerAnimated:TRUE]; [self executeSomeCode: data]; }

然而，当我运行代码时，它挂起在UIImagePicker上运行我的代码，然后在执行代码后，UIImagePicker在视觉上被解除。

有什么想法吗？

Answer 1

我意识到这不是最优雅的答案。我之前遇到过类似的问题（试图在viewDidAppear中做视觉事情但是没有用）。我发现通过调用performSelector:withObject:afterDelay:可以看到我的视觉效果。

所以在你的情况下，它将是：

[self performSelector:@selector(executeSomeCode:) withObject:data afterDelay:0];

我不知道这是否适合你（或者为什么它适用于我）。

Answer 2

没有必要使用背景方法，但您可以尝试这种方法：

- (void)_processImage:(UIImage*)image 
{
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    // convert to PNG data here, etc.
    // this is background, remember to manipulate UI in main thread
    // Example: [self.anImageView performSelectorOnMainThread:@selector(setImage:) withObject:image waitUntilDone:NO];
    [pool release];
}

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    [[picker parentViewController] dismissModalViewControllerAnimated:YES];
    UIImage *picked = [info objectForKey:@"UIImagePickerControllerOriginalImage"];
    [self performSelectorInBackground:@selector(_processImage:) withObject:[[picked retain] autorelease]];
}

Answer 3

http://developer.apple.com/iphone/library/documentation/uikit/reference/UIImagePickerControllerDelegate_Protocol/UIImagePickerControllerDelegate/UIImagePickerControllerDelegate.html

我相信您的电话已在iOS3中弃用

您可以尝试

(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info

并在解除viewController

之前从图像中获取数据

NSData *data = UIImageJPEGRepresentation( [info objectForKey:@"UIImagePickerControllerOriginalImage"] , 1.0);
[self dismissModalViewControllerAnimated:TRUE];
[self executeSomeCode:img];

Answer 4

我认为你不会挂在你认为自己的位置。据我所知，UIImagePNGRepresentation需要相当长的时间来执行（UIImageJPEGRepresentation要快得多，如果你不介意没有无损）。您可以将字典传递给您的方法并获取您需要的NSData。

您的第二个问题是您的代码是同步的，无论您多久告诉控制器解雇，它都会等待您的长代码运行。要在下一次运行循环迭代中安排繁重的代码并让控制器被解除，请使用0ms延迟来执行它。

我会将您的代码更改为：

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    [[picker parentViewController] dismissModalViewControllerAnimated:YES];
    [self performSelector:@selector(executeSomeCode:) withObject:info afterDelay:0.0f];
}

执行代码/ after / UIImagePicker被解雇

4 个答案: