上一篇文章介绍了如何进行modal方式的页面切换
自定义的目的控制器在modal切换时完全覆盖源控制器，本篇文章介绍如何实现一个自定义的过渡效果
实现的效果描述：
目的控制器：占据屏幕的二分之一大小，且居中，并在源控制器上覆盖着一个阴影效果，点击阴影时目的控制器返回
- UIPresentationController
用于描述目的控制器通过modal方式切换的过渡效果
实现其子类，可以自定义出特殊的效果
实现步骤：
- 定义过渡效果：实现UIPresentationController子类
- 目的控制器，遵循过渡协议，设置过渡控制器对象
- 源控制器进行modal切换
UIPresentationController的属性：
@property(nonatomic, retain, readonly) UIViewController *presentedViewController //目的控制器 @property(nonatomic, retain, readonly) UIViewController*presentingViewController //源控制器 - (UIView *)presentedView //目的view @property(nonatomic, readonly) UIView *containerView //源view
- UIPresentationController的子类应重写的方法
1）init方法，可以创建其他辅助过渡效果的view
- (instancetype)initWithPresentedViewController:(UIViewController*)presentedViewController presentingViewController:(UIViewController*)presentingViewController
如：
- (instancetype)initWithPresentedViewController:(UIViewController*)presentedViewController presentingViewController:(UIViewController*)presentingViewController {
if ( self = [super initWithPresentedViewController:presentedViewController presentingViewController:presentingViewController] ) {
_shadowBtn = [UIButton buttonWithType:UIButtonTypeCustom];
//阴影按钮的初始状态是隐藏的
_shadowBtn.backgroundColor = [UIColor grayColor];
_shadowBtn.alpha = 0.f;
}
}
2）重写presentationTransitionWillbegin方法，定义实现过渡效果
- (void)presentationTransitionWillBegin
如：
- (void)presentationTransitionWillBegin
{
[self.containerView addSubview:_shadowBtn];
[self.containerView addSubview:self.presentedView];
_shadowBtn.frame = self.containerView.bounds;
id <UIViewControllerTransitionCoordinator> coordinate = self.presetingViewController.transitionCoordinator;
[coordinate animateAlongsideTransition:^(id<UIViewControllerTransitionCoordinatorContext> _Nonnull context) {
_shadowBtn.alpha = 0.5;
} completion:nil];
}
使用到UIViewController的transitionCoordinator，表示过渡效果的协助器
协助器的animateAlongsideTransition方法定义过渡期间的动画效果
3）重写presentationTransitionDidEnd方法，定义过渡效果后的清理工作。
特别是过渡未完成时的清理动作
- (void)presentationTransitionDidEnd:(BOOL)completed
- (void)presentationTransitionDidEnd:(BOOL)completed
{
if ( !completed ) {
[_shadowBtn removeFromSuperview];
}
}
4）重写frameOfPresentedViewInContainerView，设置被显示视图的frame
- (CGRect)frameOfPresentedViewInContainerView
- (CGRect)frameOfPresentedViewInContainerView
{
CGFloat x, y, w, h;
w = self.containerView.frame.size.width/2;
h = self.containerView.frame.size.height/2;
x = self.containerView.frame.size.width/4;
y = self.containerView.frame.size.height/4;
return CGRectMake(x, y, w, h);
}
5）重写dismissTransitionWillBegin方法，设置返回的过渡效果
- (void)dismissalTransitionWillBegin
- (void)dismissalTransitionWillBegin
{
id<UIViewControllerTransitionCoordinator> coordinator = self.presetingViewController.transitionCoordinator;
[coordinator animateAlongsideTransition:^(id<UIViewControllerTransitionCoordinatorContext> _Nonull context) {
_shadowBtn.alpha = 0.01;
} completion:nil];
}
6）重写dismissalTransitionDidEnd方法，执行清理动作
- (void)dismissalTransitionDidEnd:(BOOL)completed
- (void)dismissalTransitionDidEnd:(BOOL)completed
{
if ( completed ) {
[_shadowView removeFromSuperview];
}
}
- 目的控制器设置过渡效果
目的控制器遵循代理协议
@interface AMDestViewController () <UIViewControllerTransitioningDelegate>
设置代理
self.transitioningDelegate = self;
实现代理方法
- (UIPresetationController *) presentationControllerForPresentedViewController:(UIViewController*) presented presentingViewController:(UIViewController*) presenting sourceViewController:(UIViewController*) source
{
return [[AMPresentationController alloc] initWithPresentedViewController:presented presentingViewController:presenting];
}
- 源控制器进行modal切换
iOS8.0开始支持这种自定义的过渡效果，主要要设置目的控制器的modalPresentationStyle为自定义。
这种切换方式，在iPhone和iPad上都是可用的。
AMDestViewController * vc = [[AMDestViewController alloct] init]; vc.modalPresentationStyle = UIModalPresentationCustom; [self presentViewController:vc animated:YES completion:nil];
时间： 2024-12-16 18:50:53