緩存圖片/文件

從網路上下載的圖片/文件，要先緩存在儲存區裡：



緩存URL圖片：

-(void)LoadImage{
  NSURL *url = [NSURL URLWithString:@"http://~.jpg"];
  NSData *data = [NSData dataWithContentsOfURL:url];
  [data writeToFile:[self GetTempPath:@"test.png"] atomically:NO];
  UIImage *img = [UIImage imageWithData:data];
}

-(NSString *)GetTempPath:(NSString*)filename{
  NSString *tempPath = NSTemporaryDirectory();
  return [tempPath stringByAppendingPathComponent:filename];
}

如果要確認文件存在否：

-(BOOL)isExistsFile:(NSString *)filepath{
  NSFileManager *filemanage = [NSFileManager defaultManager];
  return [filemanage fileExistsAtPath:filepath];
}

BOOL exist = [self isExistsFile:[self GetTempPath:@"test.png"]];

如果要存在Document內，在GetTempPath內改成：

NSArray *dirpathary = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *tempPath = [[dirpathary objectAtIndex:0] retain];