Question

I hope that title makes some sense.

I have UIView (created in IB) where I add stuff (images). Then, I have a UILabel with some text. Now, I want to make a UIImage out of that, which I do like this:

UIView *comp = [[UIView alloc] initWithFrame:self.previewView.frame];
    [comp addSubview:self.previewView];
    [comp addSubview:self.lblCaption];

    UIGraphicsBeginImageContextWithOptions(comp.bounds.size, NO, 1.0);
    [comp.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

self.previewView and self.lblCaption are both created in IB. previewView is just a screen-filling view.

The code-block is executed in an IBAction after a button-tap.

Which works wonderful, I get the image as expected and can process it further.

But after that, the contents of «self.previewView» are gone? When I do an NSLog, everything seems to be there, but it’s not visible on screen anymore.

Does anyone have an idea what’s going on here?

[Edit]

As the answer below states, the view was added to self.view before, so it was removed when I added it to the comp. The solution is pretty easy, actually, I changed the code to the following: (created a function that returns a UIImage. That’s a bit cleaner than doing it in code….

-(UIImage *)imageFromView:(UIView *)theView andLabel:(UILabel *)theLabel{

    UIGraphicsBeginImageContextWithOptions(comp.bounds.size, NO, 1.0);
    [theView.layer renderInContext:UIGraphicsGetCurrentContext()];
    [theLabel.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return viewImage;
}

Answer 1

I am just guessing assuming possible situations…

Assuming you were showing self.previewView on some other view, say self.view.

When you added self.previewView to comp, it may have been removed from self.view. (Considering that UIView.superview is only single instance, I am thinking this is very likely).

If this is the case, re-adding self.previewView to self.view after obtaining image would solve the problem.