Ios UIActivityIndicator的UIButton操作

我正试图处理这样一件事：

我有一个

ui按钮

操作，它正在调用

UIImagePickerController

并将其呈现给拍摄。但是加载需要一段时间，尤其是在第一次运行时。因此，我决定放置一个

UIActivityIndicator

，以便在加载相机时保持旋转

但是我遇到了一个问题-

UIImagePicker

正在加载主线程，因此指示器不会显示。我怎样才能解决这个问题

这是我的方法：

- (IBAction)takePhoto:(UIButton *)sender
{
    UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
    imagePicker.delegate = self;
    imagePicker.allowsEditing = YES;
    imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;

    UIActivityIndicatorView *activityView=[[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
    activityView.center=self.view.center;
    [self.view addSubview:activityView];
    [activityView startAnimating];

    [self presentViewController:imagePicker animated:NO completion:nil];
}

试试这个：

- (IBAction)takePhoto:(UIButton *)sender
{
     UIActivityIndicatorView *activityView=[[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
     activityView.center=self.view.center;
     [self.view addSubview:activityView];
     [activityView startAnimating];

     int64_t delayInSeconds = 2.0;//How long do you want to delay?
     dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
     dispatch_after(popTime, dispatch_get_main_queue(), ^(void){

         UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
         imagePicker.delegate = self;
         imagePicker.allowsEditing = YES;
         imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;

         [self presentViewController:imagePicker animated:NO completion:nil];
     });         
}

试试这个：

- (IBAction)takePhoto:(UIButton *)sender
{
     UIActivityIndicatorView *activityView=[[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
     activityView.center=self.view.center;
     [self.view addSubview:activityView];
     [activityView startAnimating];

     int64_t delayInSeconds = 2.0;//How long do you want to delay?
     dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
     dispatch_after(popTime, dispatch_get_main_queue(), ^(void){

         UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
         imagePicker.delegate = self;
         imagePicker.allowsEditing = YES;
         imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;

         [self presentViewController:imagePicker animated:NO completion:nil];
     });         
}

---

我也遇到过同样的问题，UIImagePickerController分配需要很多时间，所以为了避免主线程阻塞，您可以使用下面的代码：

- (IBAction)takePhoto:(UIButton *)sender
{
    UIActivityIndicatorView *activityView=[[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
    activityView.center=self.view.center;
    [self.view addSubview:activityView];
    [activityView startAnimating];

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
        imagePicker.delegate = self;
        imagePicker.allowsEditing = YES;
        imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;

        dispatch_async(dispatch_get_main_queue(), ^{
            [self presentViewController:imagePicker animated:NO completion:nil];
        });
    });
}

---

我也遇到过同样的问题，UIImagePickerController分配需要很多时间，所以为了避免主线程阻塞，您可以使用下面的代码：

- (IBAction)takePhoto:(UIButton *)sender
{
    UIActivityIndicatorView *activityView=[[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
    activityView.center=self.view.center;
    [self.view addSubview:activityView];
    [activityView startAnimating];

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
        imagePicker.delegate = self;
        imagePicker.allowsEditing = YES;
        imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;

        dispatch_async(dispatch_get_main_queue(), ^{
            [self presentViewController:imagePicker animated:NO completion:nil];
        });
    });
}

---

我不确定。。。我只是猜测。。。我只想在装相机的时候显示这个指示器，让一切看起来干净漂亮。怎么能花更多的时间打开你的相机呢？我不认为我加载得很慢，你需要添加活动Indicator当我点击按钮时，它会保持高位大约3秒。然后介绍了选择器。你能再详细说明一下吗，因为我在示例中使用了你的代码块，那么在我的例子中，它工作得很好，打开iris需要时间camera@frozen_lion按我想要的方式回答了我的问题我不确定。。。我只是猜测。。。我只想在装相机的时候显示这个指示器，让一切看起来干净漂亮。怎么能花更多的时间打开你的相机呢？我不认为我加载得很慢，你需要添加活动Indicator当我点击按钮时，它会保持高位大约3秒。然后介绍了选择器。你能再详细说明一下吗，因为我在示例中使用了你的代码块，那么在我的例子中，它工作得很好，打开iris需要时间camera@frozen_lion我的问题得到了我想要的答案。这个问题正是我想要的。刚刚添加了这一行：

[self-presentViewController:imagePicker动画：未完成：^{[activityView停止动画制作]；}]

以阻止此旋转死亡！这件正是我想要的。刚刚添加了这一行：

[self-presentViewController:imagePicker动画：未完成：^{[activityView停止动画制作]；}]

以阻止此旋转死亡！