How the color of attributed text inherits the parent color?

Question

For example I have to put a String "Hello, world!" in the UIButton.

And "Hello," and "world!" should be different colors.

"Hello," has the default color of UIButton, and "world!" has the customized color by NSMutableAttributedString.

I explain again with code and result.

// Using a library `SwiftyAttributes`(https://github.com/eddiekaiger/SwiftyAttributes)
button.attributedText = "Hello, ".withJust() + "world!".withTextColor(.red)

button.setTitleColor(.black, for: .normal)

I want: Hello,(black) world!(red)

button.setTitleColor(.red, for: .normal)

I want: Hello,(red) world!(red)

button.setTitleColor(.blue, for: .normal)

I want: Hello,(blue) world!(red)

But always the result is: Hello,(black) world!(red)

...

Maybe I think the priority of NSMutableAttributedString default color is higher than UIButton default color.

But can I see the result I want?

Answer 1

You seem to imagine there is some kind of "inheritance" between the title color and the color in the attributed string. There isn't. There is no relationship between them at all.

As soon as you start using attributedText, you are completely in charge of the colors in the text. The tint color and title color become completely irrelevant. If you want Hello in blue you must set it to blue in the attributed string.

Answer 2

You should indeed use NSMutableAttributedString for this purpose, but you should built up your NSMutableAttributedString instead of doing as you have done. Here is some code for you to get started with:

let attrStr = NSMutableAttributedString(string: "Hello World")
attrStr.addAttribute(NSForegroundColorAttributeName, value: UIColor.blue, range: NSRange(location: 0, length: 5))
attrStr.addAttribute(NSForegroundColorAttributeName, value: UIColor.red, range: NSRange(location: 6, length: 5))
button.setAttributedTitle(attrStr, for: .normal)

Note that the location is where you want to start the coloring and length is where you want to stop. So Hello becomes location: 0 and length: 5.

Output: