根据文件路径计算文件大小

/// 遍历文件夹获得文件夹大小，返回多少 M
- (CGFloat)folderSizeAtPath:(NSString *) folderPath{  
     
   NSFileManager * manager = [NSFileManager defaultManager];  
   if (![manager fileExistsAtPath :folderPath]) return 0 ;  
   NSEnumerator *childFilesEnumerator = [[manager subpathsAtPath :folderPath] objectEnumerator];  
   NSString * fileName;  
   long long folderSize = 0 ;  
   while ((fileName = [childFilesEnumerator nextObject]) != nil ){  
       //获取文件全路径  
       NSString * fileAbsolutePath = [folderPath stringByAppendingPathComponent :fileName];  
       folderSize += [self fileSizeAtPath :fileAbsolutePath];  
   }  
     
   return folderSize/( 1024.0 * 1024.0);  
     
} 

// 计算 单个文件的大小
- ( long long ) fileSizeAtPath:( NSString *) filePath{  
   NSFileManager * manager = [NSFileManager defaultManager];  
   if ([manager fileExistsAtPath :filePath]){  
       return [[manager attributesOfItemAtPath :filePath error : nil nil] fileSize];  
   }  
   return 0;  
}  

- (void)clearFile
{
   NSString * cachePath = [NSSearchPathForDirectoriesInDomains (NSCachesDirectory , NSUserDomainMask , YES ) firstObject];
   NSArray * files = [[NSFileManager defaultManager ] subpathsAtPath :cachePath];
   //NSLog ( @"cachpath = %@" , cachePath);
   for ( NSString * p in files) {
       
       NSError * error = nil ;
       //获取文件全路径
       NSString * fileAbsolutePath = [cachePath stringByAppendingPathComponent :p];
       
       if ([[NSFileManager defaultManager ] fileExistsAtPath :fileAbsolutePath]) {
           [[NSFileManager defaultManager ] removeItemAtPath :fileAbsolutePath error :&error];
       }
   }
   
   //读取缓存大小
   float cacheSize = [self readCacheSize] *1024;
   NSString *cacheSizeTest = [NSString stringWithFormat:@"%.2fKB",cacheSize];
   
   NSLog(@"%@",cacheSizeTest);
   
}

-(CGFloat)readCacheSize
{
   // 1.获取caches目录
   NSString *path = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
   
    NSString *cachePath =  [path stringByAppendingPathComponent:[@"articleContent" lastPathComponent]];
   

   return [self folderSizeAtPath :cachePath];
}