respond to selector method for unsupported implementations

Question

In my app I need to display under line text in a label so I used following code to display underlined text

NSMutableAttributedString *attributeString = [[NSMutableAttributedString alloc] initWithString:normalString];
    [attributeString addAttribute:NSUnderlineStyleAttributeName
                            value:[NSNumber numberWithInt:1]
                            range:(NSRange){0,[attributeString length]}];

wesiteAddressLabel.attributedText = attributeString;

This method and some other implementations which works fine in iOS 6.1

But when I executed in iOS 5.1 and below, app gets crashed due to the reason,

[attributeString addAttribute:NSUnderlineStyleAttributeName
                            value:[NSNumber numberWithInt:1]
                            range:(NSRange){0,[attributeString length]}];

not supported in previous versions

So I want to use respondsToSelector: method to check if instance responds and implement another method for unsupported selector.

How I use this method?

Answer 1

As from the documentation:

attributedText The styled text displayed by the label.

@property(nonatomic,copy) NSAttributedString *attributedText Discussion This property is nil by default. Assigning a new value to this property also replaces the value of the text property with the same string data, albeit without any formatting information. In addition, assigning a new a value updates the values in the font, textColor, and other style-related properties so that they reflect the style information starting at location 0 in the attributed string.

Availability Available in iOS 6.0 and later. Declared In UILabel.h

You should check if the a specific UIView element is able to respond to the attributedText. In this case:

[wesiteAddressLabel respondsToSelector:@selector(attributedText)];

Should be enough