User defined run time attributes are one of the hidden(likely) gems of the XCode which helps you to customise/configure your UI object in the interface builder itself, without having to write code.
The "User defined run time attributes" uses the Obejctive-C's already existed concept called Key Value Coding. With the Xcode 6, this is a game changer, see here IBInspectable and IBDesignable
Key value coding is a mechanism which helps us to access the properties of an object indirectly by name (or key, which is a string) rather than directly using the accessor method.
That means, say for example you have the property
Wait, who would do that? The
But, think of some other properties that the IB doesn't have. You can do that in the u.d.r.a (ah.,, user defined run time attributes, I am tired of typing this).
For example, here I have a custom class called
The "User defined run time attributes" uses the Obejctive-C's already existed concept called Key Value Coding. With the Xcode 6, this is a game changer, see here IBInspectable and IBDesignable
Key value coding is a mechanism which helps us to access the properties of an object indirectly by name (or key, which is a string) rather than directly using the accessor method.
That means, say for example you have the property
text for the UILabel, you can use the user defined runtime attributes for changing its value.Wait, who would do that? The
UILabel control already have the IB properties for giving the text.But, think of some other properties that the IB doesn't have. You can do that in the u.d.r.a (ah.,, user defined run time attributes, I am tired of typing this).
For example, here I have a custom class called
CustomLabel which is a subclass of UILabel which have a property called fontName. When I give string here, my CustomLabel will use this string and updates it font. I can assign the value to this fontName in the Xib itself like this.
The fun part is you can give not only key but also the key paths. (For those who doesn't know the difference between the key and the keypath,
For example, if you want to change the corner radios of a UIView, you can add a u.d.r.a with the keypath
Don't try to give the
Note:
If you give a u.d.r.a to a UI object, that doesn't have a property with that name, you will get a warning from the debugger like this. In the previous Xcode, it will raise a invalid argument exception and crash.
Here is a list of attribute types that you can use in the u.d.r.a.
For the sake of clarity, I am adding the screenshot of my
text is a key for the UILabel whereas layer.cornerRadius is a keypath for its corner radius)For example, if you want to change the corner radios of a UIView, you can add a u.d.r.a with the keypath
layer.cornerRadius.Don't try to give the
layer.borderColor in this way, because borderColor needs a CGColor object but you can only give UIColor with the u.d.r.a. If you want to achieve this, you can add a category for the CALayer with a UIColor property and you can write your own logic to change its borderColor.Note:
If you give a u.d.r.a to a UI object, that doesn't have a property with that name, you will get a warning from the debugger like this. In the previous Xcode, it will raise a invalid argument exception and crash.
Here is a list of attribute types that you can use in the u.d.r.a.
For the sake of clarity, I am adding the screenshot of my
CustomLabel class here.
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