[self.KVOController observe:vc keyPath:@"self.view" options:NSKeyValueObservingOptionInitial|NSKeyValueObservingOptionNew block:^(id observer, id object, NSDictionary *change) {

UIButton *bt = [UIButton new];

[bt setImage:[UIImage imageNamed:@"navi_close"] forState:UIControlStateNormal];

bt.frame = CGRectMake(15, 25, 40, 40);

//bt.backgroundColor = [UIColor redColor];

[vc.view addSubview:bt];

[bt setTapBlock:^(UITapGestureRecognizer *gesture) {

[vc dismissViewControllerAnimated:YES completion:nil];

self.resettingGesPwd = YES;

}];

}

];

對封裝好的視圖進行動態修改