@synthesize 与 @dynamic，有什么区别? [英] @synthesize vs @dynamic, what are the differences?

问题描述

实现 @property 和 @dynamic 或 @synthesize 有什么区别?

What are the differences between implementing a @property with @dynamic or @synthesize?

推荐答案

@synthesize 将为您的属性生成 getter 和 setter 方法.@dynamic 只是告诉编译器 getter 和 setter 方法不是由类本身实现的，而是其他地方(如超类或将在运行时提供).

@synthesize will generate getter and setter methods for your property. @dynamic just tells the compiler that the getter and setter methods are implemented not by the class itself but somewhere else (like the superclass or will be provided at runtime).

@dynamic 的用途是例如使用 NSManagedObject (CoreData) 的子类，或者当您想为未定义为插座的超类定义的属性创建插座时.

Uses for @dynamic are e.g. with subclasses of NSManagedObject (CoreData) or when you want to create an outlet for a property defined by a superclass that was not defined as an outlet.

@dynamic 也可用于委派实现访问器的责任.如果您在类中自己实现访问器，那么您通常不会使用@dynamic.

@dynamic also can be used to delegate the responsibility of implementing the accessors. If you implement the accessors yourself within the class then you normally do not use @dynamic.

超类:

@property (nonatomic, retain) NSButton *someButton;
...
@synthesize someButton;

子类:

@property (nonatomic, retain) IBOutlet NSButton *someButton;
...
@dynamic someButton;

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