UILabel外观字体和属性字符串字体

Question

In my app I have a global custom font applied to all labels like so:

UIFont *font = [UIFont fontWithName:kMyFontName size:15.0]; 
[[UILabel appearance] setFont:font];

This works fine. However, in some cases I want to be able to specify a different font for a specific region of a UILabel string.

So I have something like this:

NSString *string = @"Foo Bar Baz";
UIFont *boldFont = [UIFont fontWithName:kMyBoldFontName size:15.0]; 
NSMutableAttributedString *attrString = [[NSMutableAttributedString alloc] initWithString:string];
[attrString setAttributes:@{ NSFontAttributeName: boldFont } range:NSMakeRange(0, 3)];
self.myLabel.attributedText = attrString;

However this doesn't seem to work. I expect the "Foo" to be bold, but the entire string just has the default font. It's as if the bold font is not applied at all and is being overwritten by the font set on the UILabel appearance proxy.

When I remove the UILabel appearance line then it works fine (I can see part of the string in bold). Basically I want to have my custom font applied to the label but a separate font applied to a different region of the string. Normally this works fine with attributed strings but for some reason setting the UILabel appearance font disables this functionality (or so it seems).

• Expected results: " Foo Bar Baz"
• Actual results: "Foo Bar Baz"

If I remove the [[UILabel appearance] setFont:] line then it works:

• " Foo Bar Baz"

(but the custom font is not set on the rest of the string).

So my question is: Is there a way to specify a single font to use as the default app-wide but still be able to partially override that using attributed strings?

Also if someone can explain to me why this is not working I'd appreciate it.

Answer 1

在设置属性字符串之前将font和textColor设置为nil。

Answer 2

You can't mix and match attributed text and plain text; that's why removing the setFont method works - because when you use it, it assumes a plaintext UILabel.

NSString *string = @"Foo Bar Baz";
UIFont *boldFont = [UIFont fontWithName:kMyBoldFontName size:15.0]; 
// Define your regular font
UIFont *regularFont = [UIFont fontWithName:kMyFontName size:15.0];
NSMutableAttributedString *attrString = [[NSMutableAttributedString alloc] initWithString:string];
// And before you set the bold range, set your attributed string (the whole range!) to the new attributed font name
[attrString setAttributes:@{ NSFontAttributeName: regularFont } range:NSMakeRange(0, string.length - 1)];
[attrString setAttributes:@{ NSFontAttributeName: boldFont } range:NSMakeRange(0, 3)];
self.myLabel.attributedText = attrString;

Answer 3

There are two important parts:

1. UIAppearance applies at the moment of adding UI element to window
2. labelInstance.font = ... resets all font attributes of currently set attributed string

So if you want to keep UIAppearance customisation you have to set your custom attributed string after your label get added to window.

Reference article about how does UIAppearance work: Peter Steinberger's cool article