iphone document 图片存储和读取

存： 

//此处首先指定了图片存取路径（默认写到应用程序沙盒 中）
  NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);

  //并给文件起个文件名
  NSString *uniquePath=[[paths objectAtIndex:0] stringByAppendingPathComponent:@"pin.png"];
  BOOL blHave=[[NSFileManager defaultManager] fileExistsAtPath:uniquePath];
  if (blHave) {
      NSLog(@"already have");
      return ;
  }
  //此处的方法是将图片写到Documents文件中 如果写入成功会弹出一个警告框,提示图片保存成功
  NSString *strPathOld = [[NSBundle mainBundle] pathForResource:@"pin" ofType:@"png"];
  NSData *data = [NSData dataWithContentsOfFile:strPathOld];
  BOOL result = [data writeToFile:uniquePath atomically:YES];
  if (result) {
      NSLog(@"success");
  }else {
      NSLog(@"no success");
  }

取： 

NSFileManager *fileManager = [NSFileManager defaultManager];
  NSArray *paths = NSSearchPathForDirectoriesInDomains( NSDocumentDirectory,                                                                          NSUserDomainMask, YES);
  NSString *documentsDirectory = [paths objectAtIndex:0];
  NSString *filePath2 = [documentsDirectory stringByAppendingPathComponent:@"pin.png"];
  UIImage *img = [UIImage imageWithContentsOfFile:filePath2];
  [image setImage:img];
  NSLog(@"图片：：：：：：：：：%@",image.image);

删： 

NSFileManager* fileManager=[NSFileManager defaultManager];
   NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);

   //文件名
   NSString *uniquePath=[[paths objectAtIndex:0] stringByAppendingPathComponent:@"pin.png"];
   BOOL blHave=[[NSFileManager defaultManager] fileExistsAtPath:uniquePath];
   if (!blHave) {
       NSLog(@"no  have");
       return ;
   }else {
       NSLog(@" have");
       BOOL blDele= [fileManager removeItemAtPath:uniquePath error:nil];
       if (blDele) {
           NSLog(@"dele success");
       }else {
           NSLog(@"dele fail");
       }

   }