Creating a UIImage from a UIColor to use as a background image for UIButton

Asked 2011-06-27T17:14:57.327

160

I'm creating a colored image like this:

CGRect rect = CGRectMake(0, 0, 1, 1);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context,
                                   [[UIColor redColor] CGColor]);
//  [[UIColor colorWithRed:222./255 green:227./255 blue: 229./255 alpha:1] CGColor]) ;
CGContextFillRect(context, rect);
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

and then use it as the background image of a button:

[resultButton setBackgroundImage:img forState:UIControlStateNormal];

This works great using the redColor, however I want to use an RGB color (as shown in the commented line). When I use the RGB color, the buttons background isn't changed.

What am I missing?

Edit Report

2 Answers

Are you using ARC? The problem here is that you don't have a reference to the UIColor object that you're trying to apply; the CGColor is backed by that UIColor, but ARC will deallocate the UIColor before you have a chance to use the CGColor.

The clearest solution is to have a local variable pointing to your UIColor with the objc_precise_lifetime attribute.

You can read more about this exact case on this article about UIColor and short ARC lifetimes or get more details about the objc_precise_lifetime attribute.

answered 2012-06-27T11:57:41.417

CGContextSetFillColorWithColor(context,[[UIColor colorWithRed:(255/255.f) green:(0/255.f) blue: (0/255.f) alpha:1] CGColor]);

answered 2012-06-27T11:21:15.873

Creating a UIImage from a UIColor to use as a background image for UIButton

2 Answers

Your Answer