iOS 面试题与答案

问题 31. What is Dynamic Dispatch?

At runtime, Dynamic Dispatch determines which implementation of a polymorphic procedure, such as a method or a function, to call. This means that when we want to call our methods, such as object methods, we must use this syntax. Swift, on the other hand, does not use dynamic dispatch by default.

问题 32. What is GCD?

The GCD stands for Grand Central Dispatch. It is a low-level API that allows you to manage multiple concurrent operations. It will assist you in increasing the responsiveness of your app by deferring computationally intensive tasks to the context. It’s a simpler concurrency model than locks and threads to deal with.

问题 33. What are the advantages of the Realm framework?

• To handle all of the work, only a small amount of code is needed.
• Available in both Object C and Swift.
• SQLite and Core Data have slower performance.
• Database files can be shared easily between iOS and Android devices.
• There is no fee, no charge.
• There is no limit to the data amount that can be stored.
• Regardless of huge data sets or massive storage, consistent speed and consistency

问题 34. What are the different ways to specify the layout of elements in UIView?

Here are a few common ways to specify the layout of elements in UIView:

• Using InterfaceBuilder, we can add a XIB file to our project, layout elements within it, and then load XIB in our application code (either automatically, based on naming conventions, or manually). Also, using InterfaceBuilder, we can create a storyboard for our application.
• We can write our own code to use NSLayoutConstraints and have elements in a view arranged by Auto Layout.
• We can create CGRects describing the exact coordinates for each element and pass them to UIView’s (id)initWithFrame:(CGRect)frame method.

问题 35. What is SpriteKit and what is SceneKit?

SpriteKit is a platform for creating animated 2D objects quickly and easily.

SceneKit is a platform for 3D graphics rendering that was inherited from OS X.

SpriteKit, SceneKit, and Metal are expected to boost a new generation of mobile games that push the boundaries of what the powerful GPUs in iOS devices can do.