NSMutableAttributedString與NSString互相轉換

NSMutableAttributedString 有 add 屬性可以設定字型類型，字型顔色。在我這樣做完後，把轉換後的 NSMutableAttributedString 下的字元反賦給 NSString，

//NSString to NSMutableAttributedString
NSString *aString=@"Hello, world!";
NSMutableAttributedString *attributedString=[[NSMutableAttributedString alloc] initWithString:aString attributes:nil];
[attributedString setAttributes:@{NSForegroundColorAttributeName:[NSColor redColor]} range:NSMakeRange(0, 5)];
 
 
//NSMutableAttributedString to NSString
NSString *anotherString=[attributedString string];