Question

我有这个代码，当按下按钮时会加载一个新的UIView（来自故事板）。 goPressed函数在按下按钮时触发，它调用selectImage函数。 selectImage打开一个UIImagePickerController，让用户选择一张照片。用户选择照片后，didFinishPickingMediaWithInfo委托将所选图像添加到UIImageView。

在'goPressed'中，执行selectImage之后，它应该执行一个Segue，如注释为// 1。但没有任何反应。 performSegueWithIdentifier似乎不起作用。如果我在调用performSegueWithIdentifier之前没有调用[self selectImage]，它就可以工作了。这是代码：

- (IBAction)goPressed:(id)sender {
    [self selectImage];
    [self performSegueWithIdentifier:@"lastView" sender:currentSender]; //1
}
-(void)selectImage
{
    // Create image picker controller
    UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];

    // Set source to the camera
    imagePicker.sourceType =  UIImagePickerControllerSourceTypePhotoLibrary;

    // Delegate is self
    imagePicker.delegate = (id)self;

    // Allow editing of image ?
    imagePicker.allowsEditing=NO;


    // Show image picker
    [self presentModalViewController:imagePicker animated:YES];


}

- (void) imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    // Access the uncropped image from info dictionary
    UIImage *image = [info objectForKey:@"UIImagePickerControllerOriginalImage"];

    [[picker presentingViewController] dismissModalViewControllerAnimated:YES];


    lePreview.image= image;


}

请帮助，为什么performSegueWithIdentifier不工作？我希望我不会错过任何你需要的信息。

Answer 1

我假设您尝试使用的视图正在使用您在执行segue之前获得的图片？如果他们从图像选择器取消，你还想要塞吗？

如果它需要图片，那么也许你应该在委托电话“完成选择”后调用你的segue。

segue未触发的问题可能是由于动画仍在此处发生：

[[picker presentingViewController] dismissModalViewControllerAnimated:YES];

您可以尝试：

[[picker presentingViewController] dismissModalViewControllerAnimated:NO];

或者如果你想维护动画，将segue移动到“picker did finish”方法并按照这样做：

[self dismissModalViewControllerAnimated:YES completion:^() {
[self performSegueWithIdentifier:@"lastView" sender:self];
}];

或者如果不起作用在pickerdidfinish方法中尝试这种方法（注意 - 这应该作为调用模态视图的控制器中的委托来实现，而不是模态视图本身：

//maintain the animation
[self dismissModalViewControllerAnimated:YES];

//slight pause to let the modal page dismiss and then start the segue
double delayInSeconds = 0.5;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){

    //code to be executed on the main queue after delay

    [self performSegueWithIdentifier:@"lastView" sender:self];

});

我经常使用这种转换，然后使用模态视图轻松离开，然后在segue视图中滑动，暂停允许转换看起来很自然。

performSegueWithIdentifier无法正常工作

1 个答案: