IOS学习 NSCache 缓存类

#import "ViewController.h"

@interface ViewController ()

@property (nonatomic,strong)NSCache *cache;

@end

@implementation ViewController

-(NSCache *)cache{

    if (_cache == nil) {

        _cache = [[NSCache alloc]init];

        

        //设置数量限制,删除之前缓存的内容

        _cache.countLimit = 15;

        

        //设置代理

        _cache.delegate = self;

    }

    return _cache;

}

//开发测试时使用，一般不用：缓存中的对象将要被删除，调用此方法

-(void)cache:(NSCache *)cache willEvictObject:(id)obj{

    NSLog(@"要删除的对象obj----%@",obj);

}

- (void)viewDidLoad {

    [super viewDidLoad];

    // Do any additional setup after loading the view, typically from a nib.

}

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{

    for (int i = 0; i<20; i++) {

        NSString *str = [NSString stringWithFormat:@"hello - NO.%d",i];

        [self.cache setObject:str forKey:@(i)];

        /*@(i):[NSNumber numberWithInt:i]

         *@[]:快速加数组

         *@{}:快速加字典    */

    }

    

    for (int i = 0; i<20; i++) {

        NSString *str = [self.cache objectForKey:@(i)];

        NSLog(@"%@",str);

    }

}