Creating a UIImage from a UIImageView and a UITextView

Question

I am using the following code from a previous answer to create a new UIImage from combining a UIImageView and a UITextView.

UIView *parentView = [[UIView alloc] initWithFrame:CGRectZero];
[parentView addSubview:self.imagePreview];
[self.imagePreview setFrame:CGRectMake(0, 0, 100, 100)];
[parentView addSubview:self.memeTextFieldTop];
[self.memeTextFieldTop setFrame:CGRectMake(20, 20, 80, 20)];
[parentView sizeToFit];

UIGraphicsBeginImageContext([parentView bounds].size);
[[parentView layer] renderInContext:UIGraphicsGetCurrentContext()];
UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

The problem seems to be that I am currently getting the following errors and I am unsure how to go about solving them.

<Error>: CGContextSaveGState: invalid context 0x0
<Error>: CGContextSetAlpha: invalid context 0x0
<Error>: CGContextSaveGState: invalid context 0x0
<Error>: CGContextGetBaseCTM: invalid context 0x0
<Error>: CGContextConcatCTM: invalid context 0x0
<Error>: CGContextSetBaseCTM: invalid context 0x0
<Error>: CGContextSaveGState: invalid context 0x0
<Error>: CGContextSetAlpha: invalid context 0x0
<Error>: CGContextSaveGState: invalid context 0x0
<Error>: CGContextConcatCTM: invalid context 0x0

Any ideas how to solve this problem?

Answer 1

sizeToFit doesn't work on UIView. You have to override this method to work as you expected. See iphone uiview - resize frame to fit subviews and Having trouble getting UIView sizeToFit to do anything meaningful

Answer 2

The log shows you dont have a valid context for drawing

As per docs

UIGraphicsGetCurrentContext()

The current graphics context is nil by default. Prior to calling its drawRect: method, view objects push a valid context onto the stack, making it current. If you are not using a UIView object to do your drawing, however, you must push a valid context onto the stack manually using the UIGraphicsPushContext function.

By calling UIGraphicsPushContext() with the context you've created, your other methods can access that context with UIGraphicsGetCurrentContext().

If you're calling UIGraphicsGetCurrentContext() outside of drawRect: and haven't set a context explicitly with UIGraphicsPushContext(), the current graphics context is undefined—and certainly not safe to use