Question

我试图弄清楚为什么这不起作用

在我的tableViewcontroller viewDidLoad

中

self.headerView = [[UIView alloc] initWithFrame:CGRectMake(0, 5, 320,0)];

self.headerLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 5, 320, 0)];

self.headerLabel.textAlignment = NSTextAlignmentCenter;

self.headerLabel.text = @"text";

[self.view addSubview:self.headerView];


[self.headerView addSubview:self.headerLabel];




[UIView animateWithDuration:.5 delay:0.0 options:UIViewAnimationOptionCurveEaseIn animations:^{

    self.headerLabel.frame = CGRectMake(0, 5, 320,15);
    self.headerView.frame  = CGRectMake(0, 5, 320,15);

} completion:^(BOOL finished) {

    [UIView animateWithDuration:.5 delay:2.0 options:UIViewAnimationOptionCurveEaseIn animations:^{

        self.headerLabel.frame = CGRectMake(0, 5, 320,0);
        self.headerView.frame  = CGRectMake(0, 5, 320,0);

    } completion:^(BOOL finished) {

    }];

}];

如果我删除第一个动画调用的完成块中的幻灯片备份部分它可以工作。视图正确向下滑动。但是我无法得到它完全退缩当我在完成块中包含滑动代码时，视图不会在加载时显示，我不知道为什么而且我会疯了

Answer 1

我不确定标签为什么会消失，但您可以通过在创建视图时标记合适的高度来修复它，并且只为标签的y位置而不是其高度设置动画。

- (void)viewDidLoad {
    [super viewDidLoad];

    self.headerView = [[UIView alloc] initWithFrame:CGRectMake(0, -30, 320,30)];
    self.headerView.backgroundColor = [UIColor yellowColor];
    self.headerLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 5, 320, 21)];

    self.headerLabel.textAlignment = NSTextAlignmentCenter;

    self.headerLabel.text = @"text";

    [self.view addSubview:self.headerView];
    [self.headerView addSubview:self.headerLabel];

    [UIView animateWithDuration:.5 delay:0.0 options:UIViewAnimationOptionCurveEaseIn animations:^{
        self.headerView.frame  = CGRectMake(0, 0, 320,30);
    } completion:^(BOOL finished) {

        [UIView animateWithDuration:.5 delay:2.0 options:UIViewAnimationOptionCurveEaseIn animations:^{
            self.headerView.frame  = CGRectMake(0, -30, 320,30);

        } completion:^(BOOL finished) {

        }];

    }];
}

Answer 2

viewDidLoad并不是开始动画的最佳场所。您应该将代码移动到viewWillAppear :,如果您只希望在第一次出现视图时发生这种情况，您应该向控制器添加BOOL属性（即self.hasperformedInitialHeaderAnimation），所以：

-(void)viewWillAppear:(BOOL)animated{
[super viewWillAppear:animated];
if(!self.hasPerformedInitialHeaderAnimation){
self.hasPerformedInitalHeaderAnimation = YES;
[UIView animateWithDuration:.5 delay:0.0 options:UIViewAnimationOptionCurveEaseIn animations:^{

self.headerLabel.frame = CGRectMake(0, 5, 320,15);
self.headerView.frame  = CGRectMake(0, 5, 320,15);

} completion:^(BOOL finished) {

[UIView animateWithDuration:.5 delay:2.0 options:UIViewAnimationOptionCurveEaseIn animations:^{

    self.headerLabel.frame = CGRectMake(0, 5, 320,0);
    self.headerView.frame  = CGRectMake(0, 5, 320,0);

} completion:^(BOOL finished) {

}];
}

动画UIView向下滑动，然后向上滑动

2 个答案: