UIImagePickerController really slow when calling a

问题:

I have a view controller that is presented on pressing on one of the tabs in a tabBarController. In this view controller I initialise a UIImagePickerController in the viewDidLoad method:

- (void)viewDidLoad
{
    [super viewDidLoad];

    //Set imagePicker
    //-------------------------//
    _imagePicker = [[UIImagePickerController alloc] init];
    _imagePicker.delegate = self;
    _imagePicker.videoMaximumDuration = 10.0f;
}

The intention is to then display the UIImagePickerController at a later time when a button is pressed. For some reason though when the tab icon is pressed for this view controller, there is a 3-4 second hang while this viewDidLoad method is running. When I comment out the line _imagePicker = [[UIImagePickerController alloc] init] there is no hang time and the view controller loads immediately - as it should.

Does anyone know why allocating and initialising the UIImagePickerController is taking so long? If so, is there a way to speed it up other than running it as a background process? It seems like this is not normal behaviour.

I am using iOS7, and I am not calling viewWillAppear or viewDidAppear.

回答1:

Turns out this is only a problem when in debug mode (when the iPhone is connected and running through Xcode). Once the same app is running without being connected to Xcode the lag doesn't occur.

回答2:

Try this

//show a HUD or activityIndicator
dispatch_async(dispatch_queue_create("openPhotosCamera", NULL), ^{

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

    dispatch_async(dispatch_get_main_queue(), ^{
        //hide HUD or activityIndicator
        [presenter presentViewController:mediaUI animated:YES completion:nil];
    });
});

**presenter is yourViewController / self

回答3:

Try this.

    - (void)viewDidLoad{

    //Set imagePicker
    //-------------------------//
    _imagePicker = [[UIImagePickerController alloc] init];
    _imagePicker.delegate = self;
    _imagePicker.videoMaximumDuration = 10.0f;

[super viewDidLoad];