每次视图控制器处于活动状态时，我都会尝试打开相机

Question

我每次加载某个视图控制器时都试图打开iPhone摄像头。 然而，它只打开一次，如果我再次加载视图控制器，它不会打开相机。 每次进入视图控制器时如何打开相机？

  - (void)viewDidLoad {
[super viewDidLoad];


  UIImagePickerController *imagePickerController = [[UIImagePickerController alloc] init];

if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera])
{
    [imagePickerController setSourceType:UIImagePickerControllerSourceTypeCamera];
}

// image picker needs a delegate,
[imagePickerController setDelegate:self];

// Place image picker on the screen
[self presentModalViewController:imagePickerController animated:YES];
}

Answer 1

在以下方法中写上面的代码

- (void)viewDidAppear:(BOOL)animated {

}

Answer 2

您可能希望使用viewDidAppear:而不是viewDidLoad 。

Answer 3

写下面的代码：

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

    self.actionsheet = [[UIActionSheet alloc] initWithTitle:@"" delegate:self cancelButtonTitle:@"Cancel" destructiveButtonTitle:nil otherButtonTitles:@"Take Photo with Camera", @"Select from Library", nil];
    [self.actionsheet showInView:self.view];

  self.imgPicker=[[UIImagePickerController alloc] init];
  self.imgPicker.delegate=self;
  self.imgPicker.wantsFullScreenLayout = YES;
  self.imgPicker.allowsEditing=YES;

}


- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex
{
    if(buttonIndex == 0)
    {
        if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera])
            self.imgPicker.sourceType = UIImagePickerControllerSourceTypeCamera;
        else
            self.imgPicker.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
        [self presentViewController:self.imgPicker animated:YES completion:nil ];

        self.btnBlure.tag = 102;
    }
    else if (buttonIndex==1)
    {
        self.imgPicker.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
        [self presentViewController:self.imgPicker animated:YES completion:nil ];

        self.btnBlure.tag = 103;
    }
}

Answer 4

如果你看一下viewController life cycle ，你可以注意到

viewDidLoad（）只在第一次加载时调用，之后当你再次切换到同一个viewController时它不会调用viewDidLoad。 而不是调用viewDidLoad，它调用- (void) viewWillAppear:(BOOL)animated 。

然后你必须写下你的相机开场代码

- (void) viewWillAppear:(BOOL)animated方法

现在无论何时推送或呈现viewController，它都会打开相机。