iOS 7 UIImagePickerController has black preview

Question

I have a UIImagePickerController being called with sourceType camera and 80% of the time I get a black preview. If I wait, let\'s say around 30 seconds, I get a good preview

Answer 1

In my case I had to move some methods to the main thread.

My app creates a new Image with a new context, I can create the new context in a different thread and use the CGContext functions (like CGContextScaleCTM or CGContextTranslateCTM or CGContextConcatCTM) and [uiimage drawInRect:Mybounds];.

Basically I had to move to the main thread the renderInContext method when I drew layer in the context:

CGSize sizeView = viewPrintBase.frame.size;
UIGraphicsBeginImageContext(sizeView);
currentContext = UIGraphicsGetCurrentContext();

dispatch_sync(dispatch_get_main_queue(), ^{
    [viewPrintBase.layer renderInContext:currentContext];
    [imageViewPhotoUser.layer renderInContext:currentContext];
    if (imageViewMask) {
        [imageViewMask.layer renderInContext:currentContext];
    }
});
[imageSnapShotDrawinfView drawInRect:viewPrintBase.bounds];
UIImage *finalImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

CGImageRef imageRef = CGImageCreateWithImageInRect([finalImage CGImage], viewPrintBase.bounds);
// or use the UIImage wherever you like
imageSnapShot = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);

AlsoI had to move to the main thread all UI objects creation, like:

    __block UIView *viewPrintBase;
dispatch_sync(dispatch_get_main_queue(), ^{
    viewPrintBase = [[UIView alloc]initWithFrame:CGRectMake(0, 0, WIDTH_FINAL_IMAGE, HEIGHT_FINAL_IMAGE)];
    viewPrintBase.backgroundColor = [UIColor whiteColor];
    [viewPrintBase setClipsToBounds:YES];
    //We get the photo user
});

I hope this helps :)