Looping Through NSAttributedString Attributes to Increase Font SIze
Something like this should work:
NSMutableAttributedString *res = [self.richTextEditor.attributedText mutableCopy];
[res beginEditing];
__block BOOL found = NO;
[res enumerateAttribute:NSFontAttributeName inRange:NSMakeRange(0, res.length) options:0 usingBlock:^(id value, NSRange range, BOOL *stop) {
if (value) {
UIFont *oldFont = (UIFont *)value;
UIFont *newFont = [oldFont fontWithSize:oldFont.pointSize * 2];
[res removeAttribute:NSFontAttributeName range:range];
[res addAttribute:NSFontAttributeName value:newFont range:range];
found = YES;
}
}];
if (!found) {
// No font was found - do something else?
}
[res endEditing];
self.richTextEditor.attributedText = res;
At this point res
has a new attributed string with all fonts being twice their original size.
Here is a Swift port of maddy's answer (which works really well for me!). It's wrapped in a little extension.
import UIKit
extension NSAttributedString {
func changeFontSize(factor: CGFloat) -> NSAttributedString {
guard let output = self.mutableCopy() as? NSMutableAttributedString else {
return self
}
output.beginEditing()
output.enumerateAttribute(NSAttributedString.Key.font,
in: NSRange(location: 0, length: self.length),
options: []) { (value, range, stop) -> Void in
guard let oldFont = value as? UIFont else {
return
}
let newFont = oldFont.withSize(oldFont.pointSize * factor)
output.removeAttribute(NSAttributedString.Key.font, range: range)
output.addAttribute(NSAttributedString.Key.font, value: newFont, range: range)
}
output.endEditing()
return output
}
}
Create an NSMutableAttributedString
from your original attributed string before you start. On each iteration of the loop, call addAttribute:value:range:
on the mutable attributed string (this will replace the old attributes in that range).