UIImagePickerController没有在iOS 8中呈现 [英] UIImagePickerController not presenting in iOS 8

问题描述

其他人在iOS 8中遇到 UIImagePickerController 的问题吗？下面的方法在iPad上的iOS 7中运行得非常好，但是当我尝试呈现选择器（最后一行）时，我在XCode 6（Beta 3或4）中运行时会出现以下错误。如果重要，sourceType的选择来自同一地点的alertView。

Is anyone else having an issue with UIImagePickerController in iOS 8? The method below works perfectly well in iOS 7 on an iPad, but I get the following error when I run this in XCode 6 (Beta 3 or 4) when I try to present the picker (last line). If it matters, the selection of the sourceType is coming from an alertView that is presented in the same place.

Warning: Attempt to present <UIImagePickerController: 0x7c0ae400>  on <CAGUCreateContactViewController: 0x7bf61a00> which is already presenting (null)

打开imagePicker的方法。

Method to open imagePicker.

- (void)openPhotoPicker:(UIImagePickerControllerSourceType)sourceType
{
    if ([UIImagePickerController isSourceTypeAvailable:sourceType]) {
        NSArray *availableMediaTypes = [UIImagePickerController availableMediaTypesForSourceType:sourceType];
        if ([availableMediaTypes containsObject:(NSString *)kUTTypeImage]) {
            UIImagePickerController *imagePickerController = [[UIImagePickerController alloc] init];
            imagePickerController.modalPresentationStyle = UIModalPresentationFullScreen;
            imagePickerController.sourceType = sourceType;
            imagePickerController.mediaTypes = @[(NSString *)kUTTypeImage];
            imagePickerController.delegate = self;

            self.imagePickerController = imagePickerController;

            if (sourceType == UIImagePickerControllerSourceTypeCamera) {
                [self presentViewController:self.imagePickerController animated:YES completion:nil];
            } else {                    
                if (self.popoverVC) {
                    [self.popoverVC dismissPopoverAnimated:YES];
                    self.popoverVC = nil;
                }

                self.popoverVC = [[UIPopoverController alloc] initWithContentViewController:imagePickerController];
                [self.popoverVC presentPopoverFromRect:self.nameAndPicCell.picture.frame inView:self.view permittedArrowDirections:UIPopoverArrowDirectionUp animated:YES];
            }
        }
    }
}

推荐答案

我认为这是因为在iOS 8中，警报视图和操作表实际上是视图控制器（ UIAlertController ）。因此，如果您要呈现一个新的视图控制器以响应 UIAlertView 中的操作，那么它将在 UIAlertController 正在被解雇。我通过延迟 UIImagePickerController 的演示来解决这个问题，直到runloop的下一次迭代，通过这样做：

I think this is because in iOS 8, alert views and action sheets are actually presented view controllers (UIAlertController). So, if you're presenting a new view controller in response to an action from the UIAlertView, it's being presented while the UIAlertController is being dismissed. I worked around this by delaying the presentation of the UIImagePickerController until the next iteration of the runloop, by doing this:

[[NSOperationQueue mainQueue] addOperationWithBlock:^{
    [self openPhotoPicker:sourceType];
}];

但是，解决这个问题的正确方法是使用新的 UIAlertController iOS 8上的API（即使用 if（[UIAlertController class]） ...来测试它）。如果您尚未使用新API，这只是一种解决方法。

However, the proper way to fix this is to use the new UIAlertController API on iOS 8 (i.e. use if ([UIAlertController class]) ... to test for it). This is just a workaround if you can't use the new API yet.

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