防止按钮重复点击

[NSObject  cancelPreviousPerformRequestsWithTarget:self selector:@selector(ReloadLocalDataTable:) object:CurrentLocalPath];
LocalTextField.text=@"";
NSString *lastpath = [CurrentLocalPath stringByDeletingLastPathComponent];
self.CurrentLocalPath=[NSString stringWithFormat:@"%@",lastpath];
[self performSelector:@selector(ReloadLocalDataTable:) withObject:CurrentLocalPath afterDelay:.5];