iOS - How to use `NSMutableString` in swift
I have seen this Objective-C code but I'm struggling to do the same in swift: 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; } }];