首先在讲缓存清理之前讲讲文件管理的几个知识点
第一部分 文件管理几个常用的方法
一 比较两个文件的内容是否一样
/* -contentsEqualAtPath:andPath: does not take into account data stored in the resource fork or filesystem extended attributes.
*/
- (BOOL)contentsEqualAtPath:(NSString *)path1 andPath:(NSString *)path2;
二 路径中的文件是否存在
/* The following methods are of limited utility. Attempting to predicate behavior based on the current state of the filesystem or a particular file on the filesystem is encouraging odd behavior in the face of filesystem race conditions. It‘s far better to attempt an operation (like loading a file or creating a directory) and handle the error gracefully than it is to try to figure out ahead of time whether the operation will succeed.
*/
- (BOOL)fileExistsAtPath:(NSString *)path;
三 移除路径中文件内容
/* These methods replace their non-error returning counterparts below. See the NSFileManagerDelegate protocol below for methods that are dispatched to the NSFileManager instance‘s delegate.
*/
- (BOOL)removeItemAtPath:(NSString *)path error:(NSError **)error
四 从一个文件中读取数据
/* These methods are provided here for compatibility. The corresponding methods on NSData which return NSErrors should be regarded as the primary method of creating a file from an NSData or retrieving the contents of a file as an NSData.
*/
- (NSData *)contentsAtPath:(NSString *)path;
五 从缓存路径中取出缓存文件内容，该返回值是数组，用数组接收即可
/* subpathsAtPath: returns an NSArray of all contents and subpaths recursively from the provided path. This may be very expensive to compute for deep filesystem hierarchies, and should probably be avoided.
*/
- (NSArray *)subpathsAtPath:(NSString *)path;
六 根据文件名拼接路径
- (NSString *)stringByAppendingPathComponent:(NSString *)str;
七 根据路径计算路径中文件的大小
long long size=[fileManager attributesOfItemAtPath:path error:nil].fileSize;
第二部分 缓存清理思路的文字描述
第一步 拿到需要清理的缓存文件路径
NSString* filePath =[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
第二步 创建文件管理者
NSFileManager *fileManager=[NSFileManager defaultManager];
第三步 判断缓存文件路径中的文件内容是否存在
if ([fileManager fileExistsAtPath:path])
第四步 遍历缓存路径，拿到路径中所有文件数组
NSArray *childerFiles = [fileManager subpathsAtPath:path];
第五步 遍历数组，拼接数组
NSString *absolutePath=[path stringByAppendingPathComponent:fileName];
第六步 计算文件大小
long long size=[fileManager attributesOfItemAtPath:path error:nil].fileSize;
第三部分 缓存清理思路流程图
