是什么
NSCache 是一个类似NSDictionary的工具,当内存警告的时候,他会自动释放。
-源码
@interface NSCache <KeyType, ObjectType> : NSObject {
@private
id _delegate;
void *_private[5];
void *_reserved;
}
@property (copy) NSString *name;
@property (nullable, assign) id<NSCacheDelegate> delegate;
- (nullable ObjectType)objectForKey:(KeyType)key;
- (void)setObject:(ObjectType)obj forKey:(KeyType)key; // 0 cost
- (void)setObject:(ObjectType)obj forKey:(KeyType)key cost:(NSUInteger)g;
- (void)removeObjectForKey:(KeyType)key;
- (void)removeAllObjects;
@property NSUInteger totalCostLimit; // limits are imprecise/not strict
@property NSUInteger countLimit; // limits are imprecise/not strict
@property BOOL evictsObjectsWithDiscardedContent;
@end
@protocol NSCacheDelegate <NSObject>
@optional
- (void)cache:(NSCache *)cache willEvictObject:(id)obj;
@end
做什么
拿来可以做性能优化,可以做缓存,搭配本地数据库,在恰当的时候对数据做恰当的处理。
怎么做
1. 初始化 (NSCache)
2. 数据操作:- setObject:forKey: (写)
- objectForKey:(读)
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