iOS 面试题与答案

问题 36. Explain a singleton class.

When only one instance of a class is created in the application, that class is called a singleton class.

问题 37. Differentiate between a frame and a bound.

A UIView’s bounds are a rectangle with a size (width, height) and position (x,y) relative to its own coordinate system (0,0).

A UIView’s frame is a rectangle with a scale (width, height) and position (x,y) relative to the superview it is located within.

问题 38. How to Prioritize Usability in Design?

To prioritize usability, the design process has broken down into 4 steps:

• Consider the user’s perspective when designing the user experience.
• Users, not demographics, are what you should focus on.
• Consider all of the scenarios in which an app might be useful when promoting it.
• Even after the app has been released, continue to improve its functionality.

问题 39. What is meant by Enumerations or Enum?

A class type containing a group of related items under the same umbrella, but it is impossible to create an instance of it.

问题 40. What is the lazy property in swift?

When the property is called for the first time, an initial value of the lazy stored properties is calculated. In many situations, lazy properties come handy to developers.