@property 的属性class
作用
给类增加一个属性。(其实就是给类增加了一个setting 和getter方法,+方法,注意没有生成实例变量)
测试代码
#import <Foundation/Foundation.h> @interface ClassProperty : NSObject @property (class, nonatomic, assign, readonly) NSInteger userCount; @property (class, nonatomic, copy) NSUUID *identifier; + (void)resetIdentifier; @end #import "ClassProperty.h" static NSUUID *_identifier = nil; static NSInteger _userCount = 0; @implementation ClassProperty - (instancetype)init { self = [super init]; if (self) { _userCount += 1; } return self; } + (NSInteger)userCount { return _userCount; } + (NSUUID *)identifier { if (_identifier == nil) { _identifier = [[NSUUID alloc] init]; } return _identifier; } + (void)setIdentifier:(NSUUID *)newIdentifier { if (newIdentifier != _identifier) { _identifier = [newIdentifier copy]; } } + (void)resetIdentifier { _identifier = [[NSUUID alloc] init]; } @end ClassProperty * obj = [ClassProperty new]; NSLog(@"%d",ClassProperty.userCount); NSLog(@"%@",ClassProperty.identifier);
测试结果
2018-08-27 14:25:14.274852+0800 OriginCodeAnalytical[96276:4482776] 1
2018-08-27 14:25:14.275168+0800 OriginCodeAnalytical[96276:4482776] 544F9332-6CFC-43F6-93D6-ECB90A5D22AD
这个属性,只是增加getting setting方法,我们需要自己添加静态变量(权当类成员变量)
作者:充满活力的早晨
链接:https://www.jianshu.com/p/add91bae977e
来源:简书
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