#import "NSString+WJ.h"     @implementation NSString (WJ)     - (instancetype)cacheDir  {      //1.获取Caches目录      NSString *path = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];             //2.生成绝对路径             return [path stringByAppendingPathComponent:[self lastPathComponent]];     }     -(instancetype)docDir  {             NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentationDirectory, NSUserDomainMask, YES) lastObject];             return [path stringByAppendingPathComponent:[self lastPathComponent]];  }        - (instancetype)tmpDir  {      NSString *path = NSTemporaryDirectory();             return [path stringByAppendingPathComponent:[self lastPathComponent]];     }     @end