1.先看一下效果
左右滑动交互的TabBarController
2.在iOS7.0以前，要实现这样的效果，只有自定义TabBar了，但这很麻烦。而在iOS7.0以后，苹果在UITabBarControllerDelegate中增加了下面两个代理方法：
/**
* 实现该代理，即可以实现自定义的各界面切换时的动画(如平推，缩放，淡入淡出等)
* fromVC：当前显示的VC
* toVC：将要切换到的VC
* 返回一个自定义的切换动画，在本例中，我自定义了一个平推效果的动画
*/
- (nullable id <UIViewControllerAnimatedTransitioning>)tabBarController:(UITabBarController *)tabBarController
animationControllerForTransitionFromViewController:(UIViewController *)fromVC
toViewController:(UIViewController *)toVC NS_AVAILABLE_IOS(7_0);
/**
* 实现该代理，即可以实现与动画的交互
* tabBarController:当前的tabBarController
* animationController：动画百分比控制器
* 返回一个自定义的动画百分比控制器，以控制当前动画进行的百分比。
*/
- (nullable id <UIViewControllerInteractiveTransitioning>)tabBarController:(UITabBarController *)tabBarController
interactionControllerForAnimationController: (id <UIViewControllerAnimatedTransitioning>)animationController NS_AVAILABLE_IOS(7_0);
3.下面是实现过程
- 首先需要一个TabBarController，在本例中，我写了两个MainViewController(点击item切换时，也用自定义动画)、MainTabBarViewController(点击item是没有动画),可以在AppDelegate中选则使用哪一个。
- 在TabBarController中，添加一个pan手势
- (void)viewDidLoad {
[super viewDidLoad];
self.delegate = self;
self.selectedIndex = 0;
// 添加pan手势
_panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panGestureRecognizer:)];
[self.view addGestureRecognizer:self.panGestureRecognizer];
// 添加TabBar子控制器
壹ViewController *vc1 = [[壹ViewController alloc]init];
贰ViewController *vc2 = [[贰ViewController alloc]init];
叁ViewController *vc3 = [[叁ViewController alloc]init];
肆ViewController *vc4 = [[肆ViewController alloc]init];
伍ViewController *vc5 = [[伍ViewController alloc]init];
self.viewControllers = @[vc1,vc2,vc3,vc4,vc5];
for (int i = 0; i < self.tabBar.items.count; i ++) {
NSDictionary *dic = @{NSForegroundColorAttributeName: [UIColor colorWithRed:0.451 green:0.553 blue:0.584 alpha:1.00]};
NSDictionary *selecteddic = @{NSForegroundColorAttributeName: [UIColor colorWithRed:0.384 green:0.808 blue:0.663 alpha:1.00]};
UITabBarItem *item = [self.tabBar.items objectAtIndex:i];
[item setTitleTextAttributes:dic forState:UIControlStateNormal];
[item setTitleTextAttributes:selecteddic forState:UIControlStateSelected];
switch (i) {
case 0:
item.title = @"壹";
break;
case 1:
item.title = @"贰";
break;
case 2:
item.title = @"叁";
break;
case 3:
item.title = @"肆";
break;
case 4:
item.title = @"伍";
break;
default:
break;
}
}
}
- pan手势的实现
- (void)panGestureRecognizer:(UIPanGestureRecognizer *)pan{
// 如果没有动画控制器，则不执行动画，动画控制器就是用来展示切换动画
if (self.transitionCoordinator) {
return;
}
// 开始执行动画
if (pan.state == UIGestureRecognizerStateBegan || pan.state == UIGestureRecognizerStateChanged){
[self beginInteractiveTransitionIfPossible:pan];
}
}
- (void)beginInteractiveTransitionIfPossible:(UIPanGestureRecognizer *)sender{
// 通过滑动的方法判断应该像那边跳转
CGPoint translation = [sender translationInView:self.view];
if (translation.x > 0.f && self.selectedIndex > 0) {
self.selectedIndex --;
}
else if (translation.x < 0.f && self.selectedIndex + 1 < self.viewControllers.count) {
self.selectedIndex ++;
}
else {
if (!CGPointEqualToPoint(translation, CGPointZero)) {
sender.enabled = NO;
sender.enabled = YES;
}
}
// 告知动画控制器，开始执行动画，这里需要注意：苹果提供了两个方法，但是我们只有选择这个方法，并且只有这样写才能按我们的预期执行，否则会有BUG，这一点我也不知道原因
[self.transitionCoordinator animateAlongsideTransitionInView:self.view animation:^(id<UIViewControllerTransitionCoordinatorContext> _Nonnull context) {
} completion:^(id<UIViewControllerTransitionCoordinatorContext> _Nonnull context) {
if ([context isCancelled] && sender.state == UIGestureRecognizerStateChanged){
[self beginInteractiveTransitionIfPossible:sender];
}
}];
}
- 代理的实现
- (id<UIViewControllerAnimatedTransitioning>)tabBarController:(UITabBarController *)tabBarController animationControllerForTransitionFromViewController:(UIViewController *)fromVC toViewController:(UIViewController *)toVC{
// 判断是否是通过手势
if (self.panGestureRecognizer.state == UIGestureRecognizerStateBegan || self.panGestureRecognizer.state == UIGestureRecognizerStateChanged) {
// 判断跳转的方向
NSArray *viewControllers = tabBarController.viewControllers;
if ([viewControllers indexOfObject:toVC] > [viewControllers indexOfObject:fromVC]) {
// 返回的自定义动画
return [[TabBarTransitionAnimation alloc] initWithTargetEdge:UIRectEdgeLeft];
}
else {
return [[TabBarTransitionAnimation alloc] initWithTargetEdge:UIRectEdgeRight];
}
}
else{
// 返回空，表示用系统的动画
return nil;
}
}
- (id<UIViewControllerInteractiveTransitioning>)tabBarController:(UITabBarController *)tabBarController interactionControllerForAnimationController:(id<UIViewControllerAnimatedTransitioning>)animationController{
if (self.panGestureRecognizer.state == UIGestureRecognizerStateBegan || self.panGestureRecognizer.state == UIGestureRecognizerStateChanged) {
// 返回自定义的动画百分比控制器
return [[TabBarTransitionController alloc] initWithGestureRecognizer:self.panGestureRecognizer];
}
else {
// 返回空，表示用系统的
return nil;
}
}
- 自定义平推的动画，自定义动画需要遵守<UIViewControllerAnimatedTransitioning>协议，需要实现下面方法
// 返回动画执行时间
- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext{
return 0.35;
}
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext{
// 获取执行动画的ViewController
UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
// 获取执行动画的View，注意：该方式只有iOS8.0才有，如果要适配iOS8.0以前，请用fromViewController.view获取
UIView *fromView = [transitionContext viewForKey:UITransitionContextFromViewKey];
UIView *toView = [transitionContext viewForKey:UITransitionContextToViewKey];
// 获取执行动画前，两个view的初始frame
CGRect fromFrame = [transitionContext initialFrameForViewController:fromViewController];
CGRect toFrame = [transitionContext finalFrameForViewController:toViewController];
// 执行动画前frame的偏移向量
CGVector offset;
if (self.targetEdge == UIRectEdgeLeft){
offset = CGVectorMake(-1.f, 0.f);
}
else if (self.targetEdge == UIRectEdgeRight){
offset = CGVectorMake(1.f, 0.f);
}
else{
NSAssert(NO, @"targetEdge must be one of UIRectEdgeLeft, or UIRectEdgeRight.");
}
fromView.frame = fromFrame;
toView.frame = CGRectOffset(toFrame,
toFrame.size.width * offset.dx * -1,
toFrame.size.height * offset.dy * -1);
// 将toView添加到动画控制器中
[transitionContext.containerView addSubview:toView];
NSTimeInterval transitionDuration = [self transitionDuration:transitionContext];
// 开始执行动画
[UIView animateWithDuration:transitionDuration animations:^{
fromView.frame = CGRectOffset(fromFrame,
fromFrame.size.width * offset.dx,
fromFrame.size.height * offset.dy);
toView.frame = toFrame;
} completion:^(BOOL finished) {
// 动画执行完成
[transitionContext completeTransition:![transitionContext transitionWasCancelled]];
}];
}
- 自定义动画百分比控制器,这个苹果一个给我们定义好了一个类，我们只需要继承UIPercentDrivenInteractiveTransition，就可以轻松实现，该类主要有以下方法
// 动画时间
@property (readonly) CGFloat duration;
// 动画完成的百分比
@property (readonly) CGFloat percentComplete;
// 完成的速度
@property (nonatomic,assign) CGFloat completionSpeed;
// 动画的加速度
@property (nonatomic,assign) UIViewAnimationCurve completionCurve;
// 通过该方法来告知当前动画完成的百分比
- (void)updateInteractiveTransition:(CGFloat)percentComplete;
// 取消动画
- (void)cancelInteractiveTransition;
// 完成动画
- (void)finishInteractiveTransition;
// 本例中的实现
- (CGFloat)percentForGesture:(UIPanGestureRecognizer *)gesture{
// 通过手势在屏幕中滑动的距离来判断当前执行的百分比
UIView *transitionContainerView = self.transitionContext.containerView;
CGPoint translation = [gesture translationInView:gesture.view.superview];
if ((translation.x > 0.f && self.initialTranslationInContainerView.x < 0.f) ||
(translation.x < 0.f && self.initialTranslationInContainerView.x > 0.f)){
return -1.f;
}
return fabs(translation.x)/CGRectGetWidth(transitionContainerView.bounds);
}
// 这个手势是TabBar中传递过来的
- (void)gestureRecognizeDidUpdate:(UIScreenEdgePanGestureRecognizer *)gestureRecognizer{
switch (gestureRecognizer.state) {
case UIGestureRecognizerStateBegan:
break;
case UIGestureRecognizerStateChanged:
if ([self percentForGesture:gestureRecognizer] < 0.f) {
[self cancelInteractiveTransition];
[self.gestureRecognizer removeTarget:self action:@selector(gestureRecognizeDidUpdate:)];
}
else {
// 更新当前动画进度
[self updateInteractiveTransition:[self percentForGesture:gestureRecognizer]];
}
break;
case UIGestureRecognizerStateEnded:
if ([self percentForGesture:gestureRecognizer] >= 0.4f){
// 结束手势，动画执行大于40%时，完成动画
[self finishInteractiveTransition];
}
else{
// 否则取消动画
[self cancelInteractiveTransition];
}
break;
default:
[self cancelInteractiveTransition];
break;
}
}
4.最后附上Demo的下载地址：https://github.com/cdcyd/CommonControlsCollection
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