-(NSCache *)cache
{
if (_cache == nil) {
_cache = [[NSCache alloc]init];
_cache.totalCostLimit = 5;//总成本数是5 ,如果发现存的数据超过中成本那么会自动回收之前的对象
_cache.delegate = self;
}
return _cache;
}
//存数据
- (IBAction)addBtnClick:(id)sender
{
//NSCache的Key只是对对象进行Strong引用，不是拷贝(和可变字典的区别)
for (NSInteger i = 0; i<10; i++) {
NSData *data = [NSData dataWithContentsOfFile:@"/Users/beidou/Desktop/29381f30e924b8995d7368d66a061d950b7bf695.jpg"];
//cost:成本
[self.cache setObject:data forKey:@(i) cost:1];
NSLog(@"存数据%zd",i);
}
}
//取数据
- (IBAction)checkBtnClick:(id)sender
{
// NSLog(@"+++++++++++++++");
// for (NSInteger i = 0; i<10; i++) {
// NSData *data = [self.cache objectForKey:@(i)];
// if (data) {
// NSLog(@"取出数据%zd",i);
// }
// }
NSData *data = [self.cache objectForKey:@(8)];
if (data) {
NSLog(@"取出数据%@",data);
}
}
//删除数据
- (IBAction)removeBtnClick:(id)sender
{
[self.cache removeAllObjects];
}
#pragma mark ----------------------
#pragma mark NSCacheDelegate
//即将回收对象的时候调用该方法
-(void)cache:(NSCache *)cache willEvictObject:(id)obj
{
NSLog(@"回收%zd",[obj length]);
}
