ios - 尝试在演示过程中在 UITabBarController 上显示 UIImagePickerController

Question

我需要帮助解决警告错误。我使用 UIImagePickerController，当我点击 tabBar 上的第三个选项卡时它会显示。当我取消时，我想显示选择相机之前的最后一个选项卡，但是当我关闭我的选择器时，我收到警告!!

这是我的代码，我不明白为什么会收到警告...

-(void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    [self showPickerController];
}


- (void) showPickerController
{
    imagePicker = [[UIImagePickerController alloc] init];
    if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]){
        imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
        imagePicker.delegate = self;
    } else{
        UIAlertView *message = [[UIAlertView alloc] initWithTitle:@"Erreur !"
                                                          message:@"Votre iPhone n'a pas de Camera"
                                                         delegate:self
                                                cancelButtonTitle:@"Ok"
                                                otherButtonTitles:nil];
        [message show];
    }
    [self presentViewController:imagePicker animated:NO completion:nil];
}

#pragma mark - Camera Methods

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
    [self.tabBarController dismissViewControllerAnimated:NO completion:^{
        if(self.tabBarController!=nil)
            [self.tabBarController setSelectedIndex:0];
    }];
}

有什么想法吗？

Answer 1

除了 danh 的回答之外，向您的 View Controller 添加一个 BOOL 属性，并向您的 viewDidAppear: 方法添加一些代码:

@property (nonatomic) BOOL出现；

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];

    if (!self.appeared || [self isMovingToParentViewController] || [self isBeingPresented]) {
        self.appeared = YES;
        [self showPickerController];
    }
}

这将防止 UIImagePickerController 在被关闭后立即再次呈现。

此外，这与问题并不相关，但您可能想稍微更改 showPickerController 方法以防止显示空的 UIImagePickerController 如果没有相机可用:

- (void)showPickerController
{
    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
        imagePicker = [[UIImagePickerController alloc] init];
        imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
        imagePicker.delegate = self;
        [self presentViewController:imagePicker animated:NO completion:nil];
    }
    else {
        UIAlertView *message = [[UIAlertView alloc] initWithTitle:@"Erreur !"
                                                          message:@"Votre iPhone n'a pas de Camera"
                                                         delegate:self
                                                cancelButtonTitle:@"Ok"
                                                otherButtonTitles:nil];
        [message show];
    }
}