将自定义控件添加到Interface Builder（IB）Xcode

Question

I did this wonderful tutorial: Photoshop Tutorial For Developers: Creating a Custom UISlider and came away with two questions:

1. The example above makes every UISlider customized. Can you just subclass UISlider and tweak this code to make it it's own class that can be called upon?

2. Further, could you make this custom control available in the object explorer within Interface Builder, so you can just drag and drop it on your view like anything else in UIKit?

Answer 1

The docs for CocoaTouch classes will usually indicate if a class is not designed for sub-classing. In the case of UISlider, there's also some instructions for customizing appearance.

Custom Component in Interface Builder

To use a custom component within Interface Builder, its necessary to use the "object" component, and specify the class type to your custom class. Unfortunately this does not render any visual queues, like core UIKit classes.

Your own Plugin

It may be possible to provide a plugin to tweak Xcode, however this is no small undertaking as there are no official docs, so its necessary to search for open-source plugins on GitHub, etc and study the code. Even then, the plugin may break with subsequent version of Xcode.

Recommended Approach

Interface Builder is an amazing technology, however for more complex applications I recommend implementing views in code (override loadView in the VC). Here's some reasons:

• Promotes better encapsulation and reuse. You can compose your own components (eg composition vs inheritance) using UIKit components, and provide a custom OO interface to them. Contrast this with lots of IB outlets in a view controller, which leads to poor reuse.

• Fat-controllers don't really honor the MVC paradigm.

• More flexible and fluent. Not all properties are exposed via IB, so in a complex case, its hard to know where to look. Is that setting in IB or code? Custom fonts, for example.

• Xibs are really tricky to merge in a multi-person team.