How to change the alpha channel of an existing background color

Question

I have a UITextField that has rgb already applied to its background color. I am trying to set the alpha of the background color. How to adjust alpha without pasting all rgb color in Objective-c ?

Answer 1

You are looking for something like this:

 CGFloat newAlpha = 0.7; CGColorRef color = CGColorCreateCopyWithAlpha(self.yourTextField.layer.backgroundColor, newAlpha); [self.yourTextField.layer setBackgroundColor:color]; 

Or, if you already know the color and want only the current alpha:

 CGFloat alpha = CGColorGetAlpha(self.yourTextField.layer.backgroundColor); //Get current alpha self.yourTextField.layer.backgroundColor = [UIColor colorWithRed:1.0 green:1.0 blue:1.0 alpha:alpha].CGColor; 

Answer 2

You can use:

 UIColor *color = ...; color = [color colorWithAlphaComponent:0.5f]; 

Answer 3

In Swift 3 or 4:

 let color: UIColor = UIColor.black.withAlphaComponent(0.7)