IOS cache file clear implementation code

Mobile Internet APP application development, must always pay attention to the user experience, so as not to cause APP or mobile phones and other mobile devices stuck, the following is the processing of the cache file.

When mobile applications process network resources, they usually do offline caching, among which picture caching is the most typical. The popular offline caching framework is SDWebImage.

However, offline caching takes up storage space on the phone, so cache cleanup has become a standard feature of app for information, shopping, and reading.

The realization of offline caching function introduced today is mainly divided into the realization of obtaining and clearing cache files of the size of cache files.

1. Get the size of the cache file

-( float )readCacheSize
{
  NSString *cachePath = [NSSearchPathForDirectoriesInDomains (NSCachesDirectory , NSUserDomainMask , YES) firstObject];
  return [ self folderSizeAtPath :cachePath];
}

 

 Since the cache file is in the sandbox, we can pass NSFileManager API To realize the calculation of the size of the cache file. 
//  Iterate through the folder to get the size of the folder and how much is returned  M
- ( float ) 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 ){
    // Gets the full path to the file 
    NSString * fileAbsolutePath = [folderPath stringByAppendingPathComponent :fileName];
    folderSize += [ self fileSizeAtPath :fileAbsolutePath];
  }

  return folderSize/( 1024.0 * 1024.0);
  
}

 

//  To calculate   The size of a single file 
- ( long long ) fileSizeAtPath:( NSString *) filePath{
  NSFileManager * manager = [NSFileManager defaultManager];
  if ([manager fileExistsAtPath :filePath]){
    return [[manager attributesOfItemAtPath :filePath error : nil] fileSize];
  }
  return 0;
}

 

2. Clear the cache

- (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 ;
    // Gets the full path to the file 
    NSString * fileAbsolutePath = [cachePath stringByAppendingPathComponent :p];
    
    if ([[NSFileManager defaultManager ] fileExistsAtPath :fileAbsolutePath]) {
      [[NSFileManager defaultManager ] removeItemAtPath :fileAbsolutePath error :&error];
    }
  }
  
  // Read cache size 
  float cacheSize = [self readCacheSize] *1024;
  self.cacheSize.text = [NSString stringWithFormat:@"%.2fKB",cacheSize];

}


 

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