Creating a UIImage from a UIColor to use as a background image for UIButton [duplicate]
I created a category around UIButton to be able to set the background color of the button and set the state. You might find this useful.
@implementation UIButton (ButtonMagic)- (void)setBackgroundColor:(UIColor *)backgroundColor forState:(UIControlState)state { [self setBackgroundImage:[UIButton imageFromColor:backgroundColor] forState:state];}+ (UIImage *)imageFromColor:(UIColor *)color { CGRect rect = CGRectMake(0, 0, 1, 1); UIGraphicsBeginImageContext(rect.size); CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSetFillColorWithColor(context, [color CGColor]); CGContextFillRect(context, rect); UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return image;}
This will be part of a set of helper categories I'm open sourcing this month.
Swift 2.2
extension UIImage {static func fromColor(color: UIColor) -> UIImage { let rect = CGRect(x: 0, y: 0, width: 1, height: 1) UIGraphicsBeginImageContext(rect.size) let context = UIGraphicsGetCurrentContext() CGContextSetFillColorWithColor(context, color.CGColor) CGContextFillRect(context, rect) let img = UIGraphicsGetImageFromCurrentImageContext() UIGraphicsEndImageContext() return img }}
Swift 3.0
extension UIImage { static func from(color: UIColor) -> UIImage { let rect = CGRect(x: 0, y: 0, width: 1, height: 1) UIGraphicsBeginImageContext(rect.size) let context = UIGraphicsGetCurrentContext() context!.setFillColor(color.cgColor) context!.fill(rect) let img = UIGraphicsGetImageFromCurrentImageContext() UIGraphicsEndImageContext() return img! }}
Use as
let img = UIImage.from(color: .black)
Xamarin.iOS solution
public UIImage CreateImageFromColor() { var imageSize = new CGSize(30, 30); var imageSizeRectF = new CGRect(0, 0, 30, 30); UIGraphics.BeginImageContextWithOptions(imageSize, false, 0); var context = UIGraphics.GetCurrentContext(); var red = new CGColor(255, 0, 0); context.SetFillColor(red); context.FillRect(imageSizeRectF); var image = UIGraphics.GetImageFromCurrentImageContext(); UIGraphics.EndImageContext(); return image; }
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.