IOS Face Questions

1. What are the sub-categories of calayer? Use?

2. What are the common Crash scenes?

3. How to use the @protocol and category @property

4. What is method swizzling?

5, how to make their own class with the copy modifier? How do I rewrite the setter with the Copy keyword?

6. What is the iOS signature mechanism about?

Answer:

1. What are the sub-categories of calayer? Use?

Cashaperlayer

Cagradientlayer: Color transitions

Caemitterylayer: Particle effects

Catransformlayer: Constructs a hierarchical 3D structure by adding depth of field to a layer.

Careplicatorlayer: Layer Copy

Cascrolllayer

Catiledlayer: Provides a way to save memory rendering overhead

Catextlayer:

Caeagllayer:

Avplayerlayer: Play Video

2. What are the common Crash scenes?

Array out of bounds

The Zombie object was accessed. Objects that have been released

Access the wild pointer. Exc_bad_access.

A method that does not exist is accessed. Unrecognized selector

Multithreading concurrent Operations

Release the timer before the timer next callback

3. How to use the @protocol and category @property

Objc_setassociatedobject/objc_setassociatedobject

4. What is method swizzling?

In short, it's a method exchange.

Calling a method in Objective-c is actually sending a message to an object, and the only way to find the message is by selector's name. By using the dynamic characteristics of objective-c, we can implement the corresponding method of the selector in the runtime, and achieve the purpose of linking to the method.

Each class has a list of methods, the name of the method and the method to implement the mapping relationship, the essence of selector is actually the method name, imp a bit like a function pointer, pointing to the specific method implementation, through selector can find the corresponding imp.

Selector--and corresponding IMP

Several ways to realize the Exchange method

Implementation of two methods using Method_exchangeimplementations Exchange

Implementation of using Class_replacemethod substitution method

Use Method_setimplementation to directly set up an imp for a method.

5, how to make their own class with the copy modifier? How do I rewrite the setter with the Copy keyword?

6. What is the iOS signature mechanism about?

5, how to make their own class with the copy modifier? How do I rewrite the setter with the Copy keyword?

The Nscopying protocol is required if you want the object you write to have a copy function. If a custom object is divided into a mutable version and an immutable version, then both the Nscopyiog and nsmutablecopying protocols are implemented.

6.

https://www.jianshu.com/p/ad29445eb91c

IOS Face Questions