UIKit & graphicsHistorical technical note
Recreating pop-up effects from Jianshu and Taobao on iOS
Separates the effect into content, a dimming overlay and the presented view. Two-stage layer transforms and dismissal animation make the background appear to recede, while the article explains the stacking order when adding views to a window.
Originally credited to WzxJiang; edited and archived by Bison.
Source listed in the originalOn this page
Editor: Bison
Contributor: WzxJiang
“While using the Jianshu App yesterday, I noticed how smooth and appealing this View's popup effect was. I tried implementing it myself and achieved almost the same effect:”
Let's begin: 1. How many views does this screen contain? There are four: self.view; the white view controller's view, rootVC.view; its overlay, maskView ; and the popup, popView. Create them as follows:
self.view.backgroundColor = [UIColor blackColor];
_popView = ({
UIView * popView = [[UIView alloc]initWithFrame:CGRectMake(0, [UIScreen mainScreen].bounds.size.height, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height /2.0)];
popView.backgroundColor = [UIColor grayColor];
//加个阴影
popView.layer.shadowColor = [UIColor blackColor].CGColor;
popView.layer.shadowOffset = CGSizeMake(0.5, 0.5);
popView.layer.shadowOpacity = 0.8;
popView.layer.shadowRadius = 5;
//关闭btn
UIButton * closeBtn = [UIButton buttonWithType:UIButtonTypeCustom];
closeBtn.frame = CGRectMake(15, 0, 50, 40);
[closeBtn setTitle:@"关闭" forState:UIControlStateNormal];
[closeBtn setTitleColor:[UIColor colorWithRed:217/255.0 green:110/255.0 blue:90/255.0 alpha:1] forState:UIControlStateNormal];
[closeBtn addTarget:self action:@selector(close) forControlEvents:UIControlEventTouchUpInside];
[popView addSubview:closeBtn];
popView;
});
//添加VC的View的方法
_rootVC.view.frame = self.view.bounds;
_rootVC.view.backgroundColor = [UIColor whiteColor];
_rootview = _rootVC.view;
[self addChildViewController:_rootVC];
[self.view addSubview:_rootview];
//rootVC上的maskView
_maskView = ({
UIView * maskView = [[UIView alloc]initWithFrame:self.view.bounds];
maskView.backgroundColor = [UIColor colorWithWhite:0 alpha:0.5];
maskView.alpha = 0;
maskView;
});
[_rootview addSubview:_maskView];
2. Add a tap event. For convenience, I use touchesBegan directly to trigger the popup.
- (void)show
{
[[UIApplication sharedApplication].windows[0] addSubview:_popView];
CGRect frame = _popView.frame;
frame.origin.y = self.view.frame.size.height/2.0;
[UIView animateWithDuration:0.3 delay:0 options:UIViewAnimationOptionCurveEaseInOut animations:^{
[_rootview.layer setTransform:[self firstTransform]];
} completion:^(BOOL finished) {
[UIView animateWithDuration:0.3 delay:0 options:UIViewAnimationOptionCurveEaseInOut animations:^{
[_rootview.layer setTransform:[self secondTransform]];
//显示maskView
[_maskView setAlpha:0.5f];
//popView上升
_popView.frame = frame;
} completion:^(BOOL finished) {
}];
}];
}
Note that popview is added to the window:
[[UIApplication sharedApplication].windows[0] addSubview:_popView];
Now comes the key layer-transform method.
- (CATransform3D)firstTransform{
CATransform3D t1 = CATransform3DIdentity;
t1.m34 = 1.0/-900;
//带点缩小的效果
t1 = CATransform3DScale(t1, 0.95, 0.95, 1);
//绕x轴旋转
t1 = CATransform3DRotate(t1, 15.0 * M_PI/180.0, 1, 0, 0);
return t1;
}
- (CATransform3D)secondTransform{
CATransform3D t2 = CATransform3DIdentity;
t2.m34 = [self firstTransform].m34;
//向上移
t2 = CATransform3DTranslate(t2, 0, self.view.frame.size.height * (-0.08), 0);
//第二次缩小
t2 = CATransform3DScale(t2, 0.8, 0.8, 1);
return t2;
}
At this point, you should be able to see that two transformations take place.
3. Hide animation
- (void)close
{
_isShow = NO;
CGRect frame = _popView.frame;
frame.origin.y += self.view.frame.size.height/2.0;
[UIView animateWithDuration:0.3 delay:0 options:UIViewAnimationOptionCurveEaseInOut animations:^{
//maskView隐藏
[_maskView setAlpha:0.f];
//popView下降
_popView.frame = frame;
} completion:^(BOOL finished) {
[UIView animateWithDuration:0.3 delay:0 options:UIViewAnimationOptionCurveEaseInOut animations:^{
//变为初始值
[_rootview.layer setTransform:CATransform3DIdentity];
} completion:^(BOOL finished) {
//移除
[_popView removeFromSuperview];
}];
}];
[UIView animateWithDuration:0.3 delay:0 options:UIViewAnimationOptionCurveEaseInOut animations:^{
//和上个动画同时进行 感觉更丝滑
[_rootview.layer setTransform:[self firstTransform]];
} completion:^(BOOL finished) {
}];
}
The important point is that the two animations run simultaneously, producing a very smooth result!
Finally, here is the complete, encapsulated code. Inherit from it and call the creation method to use it.
GitHub: Wzxhaha
Recommended reading: Bison's guide to iOS multithreading, part 1