这个动画有什么问题，用于调出一个选取器视图

Question

动画之前的所有代码：

int height = 255;
//create new view
self.NewView = [[UIView alloc] initWithFrame:CGRectMake(0, 200, 320, height)];
self.NewView.backgroundColor = [UIColor colorWithWhite:1 alpha:1];
//add toolbar
UIToolbar * toolbar = [[UIToolbar alloc] initWithFrame: CGRectMake(0, 0, 320, 45)];
toolbar.barStyle = UIBarStyleBlack;
//add buttons
UIBarButtonItem *infoButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Done" style:UIBarButtonItemStyleDone target:nil action:@selector(dismissCustom:)];
UIBarButtonItem *flexible = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];
UIBarButtonItem *cancelButton = [[UIBarButtonItem alloc] initWithTitle:@"Cancel" style:UIBarButtonItemStyleBordered target:nil action:@selector(cancelView:)];
toolbar.items = [NSArray arrayWithObjects:cancelButton, flexible, infoButtonItem, nil];
//add date picker
self.datePicker = [[UIDatePicker alloc] init];
self.datePicker.datePickerMode = UIDatePickerModeDateAndTime ;
self.datePicker.hidden = NO;
self.datePicker.date = [NSDate date];
self.datePicker.frame = CGRectMake(0, 40, 320, 250);
[self.datePicker addTarget:self action:nil forControlEvents:UIControlEventValueChanged];
[self.NewView addSubview:self.datePicker];
[self.NewView addSubview:toolbar];

使视图可见的动画代码：

 __block CGRect temp = self.NewView.frame;
    temp.origin.y = CGRectGetMaxY(self.view.bounds);
    [UIView animateWithDuration:0.5 animations:^{temp.origin.y -= height, self.NewView.frame = temp;} completion:^(BOOL finished) {
        [self.view addSubview:self.NewView];}];

我有几乎相同的代码来摆脱它，它工作正常！

int height = 0;
__block CGRect temp = self.NewView.frame;
temp.origin.y = CGRectGetMaxY(self.view.bounds);
[UIView animateWithDuration:0.5 animations:^{temp.origin.y -= height, self.NewView.frame = temp;} completion:^(BOOL finished) {
    [self.NewView removeFromSuperview];}];

有人知道出了什么问题吗？视图也只是出现在它应该滑动的位置。

Answer 1

问题是您仅在动画完成后才将 NewView 添加为子视图。您必须在之前添加它，如下所示：

__block CGRect temp = self.NewView.frame;
temp.origin.y = CGRectGetMaxY(self.view.bounds);
[self.view addSubview:self.NewView];
[UIView animateWithDuration:0.5 animations:^{temp.origin.y -= height, self.NewView.frame = temp;} completion:nil];