iOS基于YYCache 改造，支持缓存 KEY 过期

一、关于yycache

开发 iOS 的老铁们对 yykit 应该非常熟悉了，不熟悉的可直接移步至：https://github.com/ibireme/YYCache，非常牛逼。

二、本文介绍

最近项目中遇到一个场景，需要指定某个 key 在存储时可指定有效期，若过期，则删除改 KEY 并 return nil，话不多说先上代码，文末讲大致的实现逻辑。
核心代码主要在YYCache.m 文件中

//
//  YYCache.m
//  YYCache <https://github.com/ibireme/YYCache>
//
//  Created by ibireme on 15/2/13.
//  Copyright (c) 2015 ibireme.
//
//  This source code is licensed under the MIT-style license found in the
//  LICENSE file in the root directory of this source tree.
//#import "YYCache.h"
#import "YYMemoryCache.h"
#import "YYDiskCache.h"//过期时间标识
static NSString * const EXPIRE_TIME = @"expire_time_";
@implementation YYCache- (instancetype) init {NSLog(@"Use \"initWithName\" or \"initWithPath\" to create YYCache instance.");return [self initWithPath:@""];
}- (instancetype)initWithName:(NSString *)name {if (name.length == 0) return nil;NSString *cacheFolder = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) firstObject];NSString *path = [cacheFolder stringByAppendingPathComponent:name];return [self initWithPath:path];
}- (instancetype)initWithPath:(NSString *)path {if (path.length == 0) return nil;YYDiskCache *diskCache = [[YYDiskCache alloc] initWithPath:path];if (!diskCache) return nil;NSString *name = [path lastPathComponent];YYMemoryCache *memoryCache = [YYMemoryCache new];memoryCache.name = name;self = [super init];_name = name;_diskCache = diskCache;_memoryCache = memoryCache;return self;
}+ (instancetype)cacheWithAppId:(NSString *)appid {return [[self alloc] initWithName:appid];
}+ (instancetype)cacheWithPath:(NSString *)path {return [[self alloc] initWithPath:path];
}- (BOOL)containsObjectForKey:(NSString *)key {//判断是否过期BOOL b = [self checkKeyIsExpire:key];if (b) {return NO;}return [_memoryCache containsObjectForKey:key] || [_diskCache containsObjectForKey:key];
}- (void)containsObjectForKey:(NSString *)key withBlock:(void (^)(NSString *key, BOOL contains))block {if (!block) return;//判断是否过期BOOL b = [self checkKeyIsExpire:key];if (b) {[self removeObjectForKey:key];dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{block(key, NO);});}else{if ([_memoryCache containsObjectForKey:key]) {dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{block(key, YES);});} else  {[_diskCache containsObjectForKey:key withBlock:block];}}
}- (id<NSCoding>)objectForKey:(NSString *)key {//判断是否过期BOOL b = [self checkKeyIsExpire:key];if (b) {[self removeObjectForKey:key];return nil;}id<NSCoding> object = [_memoryCache objectForKey:key];if (!object) {object = [_diskCache objectForKey:key];if (object) {[_memoryCache setObject:object forKey:key];}}return object;
}- (void)objectForKey:(NSString *)key withBlock:(void (^)(NSString *key, id<NSCoding> object))block {if (!block) return;//判断是否过期BOOL b = [self checkKeyIsExpire:key];if (b) {[self removeObjectForKey:key];return ;}id<NSCoding> object = [_memoryCache objectForKey:key];if (object) {dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{block(key, object);});} else {[_diskCache objectForKey:key withBlock:^(NSString *key, id<NSCoding> object) {if (object && ![_memoryCache objectForKey:key]) {[_memoryCache setObject:object forKey:key];}block(key, object);}];}
}- (void)setObject:(id<NSCoding>)object forKey:(NSString *)key {[_memoryCache setObject:object forKey:key];[_diskCache setObject:object forKey:key];
}- (void)setObject:(id<NSCoding>)object forKey:(NSString *)key withBlock:(void (^)(void))block {[_memoryCache setObject:object forKey:key];[_diskCache setObject:object forKey:key withBlock:block];
}- (void)setObject:(nullable id<NSCoding>)object forKey:(NSString *)key expiretime:(int)expiretime{[_memoryCache setObject:object forKey:key];[_diskCache setObject:object forKey:key];//存储过期时间NSString *timeKey = [self getTimeKey:key];NSString *timeValue = [self getTimeValue:expiretime];[_memoryCache setObject:timeValue forKey:timeKey];[_diskCache setObject:timeValue forKey:timeKey];}- (void)setObject:(nullable id<NSCoding>)object forKey:(NSString *)key expiretime:(int)expiretime withBlock:(nullable void(^)(void))block{[_memoryCache setObject:object forKey:key];[_diskCache setObject:object forKey:key withBlock:block];//存储过期时间NSString *timeKey = [self getTimeKey:key];NSString *timeValue = [self getTimeValue:expiretime];[_memoryCache setObject:timeValue forKey:timeKey];[_diskCache setObject:timeValue forKey:timeKey withBlock:nil];
}- (void)removeObjectForKey:(NSString *)key {[_memoryCache removeObjectForKey:key];[_diskCache removeObjectForKey:key];//删除时间 KEYNSString *timeKey = [self getTimeKey:key];[_memoryCache removeObjectForKey:timeKey];[_diskCache removeObjectForKey:timeKey];
}- (void)removeObjectForKey:(NSString *)key withBlock:(void (^)(NSString *key))block {[_memoryCache removeObjectForKey:key];[_diskCache removeObjectForKey:key withBlock:block];//删除时间 KEYNSString *timeKey = [self getTimeKey:key];[_diskCache removeObjectForKey:timeKey withBlock:nil];[_diskCache removeObjectForKey:timeKey];}- (void)removeAllObjects {[_memoryCache removeAllObjects];[_diskCache removeAllObjects];
}- (void)removeAllObjectsWithBlock:(void(^)(void))block {[_memoryCache removeAllObjects];[_diskCache removeAllObjectsWithBlock:block];
}- (void)removeAllObjectsWithProgressBlock:(void(^)(int removedCount, int totalCount))progressendBlock:(void(^)(BOOL error))end {[_memoryCache removeAllObjects];[_diskCache removeAllObjectsWithProgressBlock:progress endBlock:end];}- (NSString *)description {if (_name) return [NSString stringWithFormat:@"<%@: %p> (%@)", self.class, self, _name];else return [NSString stringWithFormat:@"<%@: %p>", self.class, self];
}/// 获取当前 秒的时间戳
-(NSString *)getNowTimeTimestamp{NSDate* dat = [NSDate dateWithTimeIntervalSinceNow:0];NSTimeInterval a=[dat timeIntervalSince1970];NSString*timeString = [NSString stringWithFormat:@"%0.f", a];return timeString;
}///为 KEY 追加时间字符
-(NSString *)getTimeKey:(NSString *)key{NSString *timeKey = [NSString stringWithFormat:@"%@%@",EXPIRE_TIME,key];return timeKey;
}/// 组装时间 value
/// @param expiretime 过期时间
-(NSString *)getTimeValue:(int)expiretime {NSString *timestamp = [self getNowTimeTimestamp];NSString *timeValue = [NSString stringWithFormat:@"%@-%d",timestamp,expiretime];return timeValue;
}根据 key 反查时间 KEY
-(BOOL)checkKeyIsExpire:(NSString *)key{NSString * timeKey = [self getTimeKey:key];id<NSCoding> timeValue = [_memoryCache objectForKey:timeKey];if (!timeValue) {timeValue = [_diskCache objectForKey:timeKey];if (timeValue) {[_memoryCache setObject:timeValue forKey:timeKey];}}if(timeValue == nil){return NO;}NSString *timeStringValue = [NSString stringWithFormat:@"%@",timeValue];//分隔 “时间戳-过期时间”@try {NSArray *array = [timeStringValue componentsSeparatedByString:@"-"];NSString *expireTimeStamp = array[0];NSString *expiretime = array[1];int longExpireTimeStamp = [expireTimeStamp intValue];int intExpiretime = [expiretime intValue];int longNewTimeStamp = [[self getNowTimeTimestamp] intValue];int t = longNewTimeStamp - longExpireTimeStamp;if (t >= intExpiretime) {//删除过期的 时间 key[self removeObjectForKey:key];[self removeObjectForKey:timeKey];return YES;}} @catch (NSException *exception) {return NO;NSLog(@"%@", exception.description);}return NO;
}@end

YYCache.h 文件

//
//  YYCache.h
//  YYCache <https://github.com/ibireme/YYCache>
//
//  Created by ibireme on 15/2/13.
//  Copyright (c) 2015 ibireme.
//
//  This source code is licensed under the MIT-style license found in the
//  LICENSE file in the root directory of this source tree.
//#import <Foundation/Foundation.h>#if __has_include(<YYCache/YYCache.h>)
FOUNDATION_EXPORT double YYCacheVersionNumber;
FOUNDATION_EXPORT const unsigned char YYCacheVersionString[];
#import <YYCache/YYMemoryCache.h>
#import <YYCache/YYDiskCache.h>
#import <YYCache/YYKVStorage.h>
#elif __has_include(<YYWebImage/YYCache.h>)
#import <YYWebImage/YYMemoryCache.h>
#import <YYWebImage/YYDiskCache.h>
#import <YYWebImage/YYKVStorage.h>
#else
#import "YYMemoryCache.h"
#import "YYDiskCache.h"
#import "YYKVStorage.h"
#endifNS_ASSUME_NONNULL_BEGIN/**`YYCache` is a thread safe key-value cache.It use `YYMemoryCache` to store objects in a small and fast memory cache,and use `YYDiskCache` to persisting objects to a large and slow disk cache.See `YYMemoryCache` and `YYDiskCache` for more information.*/
@interface YYCache : NSObject/** The name of the cache, readonly. */
@property (copy, readonly) NSString *name;/** The underlying memory cache. see `YYMemoryCache` for more information.*/
@property (strong, readonly) YYMemoryCache *memoryCache;/** The underlying disk cache. see `YYDiskCache` for more information.*/
@property (strong, readonly) YYDiskCache *diskCache;/**Create a new instance with the specified name.Multiple instances with the same name will make the cache unstable.@param name  The name of the cache. It will create a dictionary with the name inthe app's caches dictionary for disk cache. Once initialized you should not read and write to this directory.@result A new cache object, or nil if an error occurs.*/
- (nullable instancetype)initWithName:(NSString *)name;/**Create a new instance with the specified path.Multiple instances with the same name will make the cache unstable.@param path  Full path of a directory in which the cache will write data.Once initialized you should not read and write to this directory.@result A new cache object, or nil if an error occurs.*/
- (nullable instancetype)initWithPath:(NSString *)path NS_DESIGNATED_INITIALIZER;/**根据a appid 初始化缓存实例@param name  The name of the cache. It will create a dictionary with the name inthe app's caches dictionary for disk cache. Once initialized you should not read and write to this directory.@result A new cache object, or nil if an error occurs.*/
+ (nullable instancetype)cacheWithAppId:(NSString *)appid;/**Convenience InitializersCreate a new instance with the specified path.Multiple instances with the same name will make the cache unstable.@param path  Full path of a directory in which the cache will write data.Once initialized you should not read and write to this directory.@result A new cache object, or nil if an error occurs.*/
+ (nullable instancetype)cacheWithPath:(NSString *)path;- (instancetype)init UNAVAILABLE_ATTRIBUTE;
+ (instancetype)new UNAVAILABLE_ATTRIBUTE;#pragma mark - Access Methods
///=============================================================================
/// @name Access Methods
///=============================================================================/**Returns a boolean value that indicates whether a given key is in cache.This method may blocks the calling thread until file read finished.@param key A string identifying the value. If nil, just return NO.@return Whether the key is in cache.*/
- (BOOL)containsObjectForKey:(NSString *)key;/**Returns a boolean value with the block that indicates whether a given key is in cache.This method returns immediately and invoke the passed block in background queuewhen the operation finished.@param key   A string identifying the value. If nil, just return NO.@param block A block which will be invoked in background queue when finished.*/
- (void)containsObjectForKey:(NSString *)key withBlock:(nullable void(^)(NSString *key, BOOL contains))block;/**Returns the value associated with a given key.This method may blocks the calling thread until file read finished.@param key A string identifying the value. If nil, just return nil.@return The value associated with key, or nil if no value is associated with key.*/
- (nullable id<NSCoding>)objectForKey:(NSString *)key;/**Returns the value associated with a given key.This method returns immediately and invoke the passed block in background queuewhen the operation finished.@param key A string identifying the value. If nil, just return nil.@param block A block which will be invoked in background queue when finished.*/
- (void)objectForKey:(NSString *)key withBlock:(nullable void(^)(NSString *key, id<NSCoding> object))block;/**Sets the value of the specified key in the cache.This method may blocks the calling thread until file write finished.@param object The object to be stored in the cache. If nil, it calls `removeObjectForKey:`.@param key    The key with which to associate the value. If nil, this method has no effect.*/
- (void)setObject:(nullable id<NSCoding>)object forKey:(NSString *)key;/**Sets the value of the specified key in the cache.This method returns immediately and invoke the passed block in background queuewhen the operation finished.@param object The object to be stored in the cache. If nil, it calls `removeObjectForKey:`.@param block  A block which will be invoked in background queue when finished.*/
- (void)setObject:(nullable id<NSCoding>)object forKey:(NSString *)key withBlock:(nullable void(^)(void))block;/**Sets the value of the specified key in the cache.This method may blocks the calling thread until file write finished.@param object The object to be stored in the cache. If nil, it calls `removeObjectForKey:`.@param key    The key with which to associate the value. If nil, this method has no effect.@param expiretime 过期时间*/
- (void)setObject:(nullable id<NSCoding>)object forKey:(NSString *)key expiretime:(int)expiretime;/**Sets the value of the specified key in the cache.This method returns immediately and invoke the passed block in background queuewhen the operation finished.@param object The object to be stored in the cache. If nil, it calls `removeObjectForKey:`.@param block  A block which will be invoked in background queue when finished.@param expiretime 过期时间*/
- (void)setObject:(nullable id<NSCoding>)object forKey:(NSString *)key expiretime:(int)expiretime withBlock:(nullable void(^)(void))block;/**Removes the value of the specified key in the cache.This method may blocks the calling thread until file delete finished.@param key The key identifying the value to be removed. If nil, this method has no effect.*/
- (void)removeObjectForKey:(NSString *)key;/**Removes the value of the specified key in the cache.This method returns immediately and invoke the passed block in background queuewhen the operation finished.@param key The key identifying the value to be removed. If nil, this method has no effect.@param block  A block which will be invoked in background queue when finished.*/
- (void)removeObjectForKey:(NSString *)key withBlock:(nullable void(^)(NSString *key))block;/**Empties the cache.This method may blocks the calling thread until file delete finished.*/
- (void)removeAllObjects;/**Empties the cache.This method returns immediately and invoke the passed block in background queuewhen the operation finished.@param block  A block which will be invoked in background queue when finished.*/
- (void)removeAllObjectsWithBlock:(void(^)(void))block;/**Empties the cache with block.This method returns immediately and executes the clear operation with block in background.@warning You should not send message to this instance in these blocks.@param progress This block will be invoked during removing, pass nil to ignore.@param end      This block will be invoked at the end, pass nil to ignore.*/
- (void)removeAllObjectsWithProgressBlock:(nullable void(^)(int removedCount, int totalCount))progressendBlock:(nullable void(^)(BOOL error))end;@endNS_ASSUME_NONNULL_END

三、新增的 API 如下

/**Sets the value of the specified key in the cache.This method may blocks the calling thread until file write finished.@param object The object to be stored in the cache. If nil, it calls `removeObjectForKey:`.@param key    The key with which to associate the value. If nil, this method has no effect.@param expiretime 过期时间*/
- (void)setObject:(nullable id<NSCoding>)object forKey:(NSString *)key expiretime:(int)expiretime;/**Sets the value of the specified key in the cache.This method returns immediately and invoke the passed block in background queuewhen the operation finished.@param object The object to be stored in the cache. If nil, it calls `removeObjectForKey:`.@param block  A block which will be invoked in background queue when finished.@param expiretime 过期时间*/
- (void)setObject:(nullable id<NSCoding>)object forKey:(NSString *)key expiretime:(int)expiretime withBlock:(nullable void(^)(void))block;/**

四、实现思路

1、在存储KEY 的时候根据 KEY 存储当前创建或者更新时间
2、在取 KEY 的时候，首先获取系统当前时间并和存储时间相减，如果大于设置的过期时间则自动删除改 KEY并返回 nil。

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