在我們開發的過程中，有時會有左右側滑tabbarViewController切換控制器的需求，在我自己做項目的時候遇到了此類需求，現在就在此記錄一下我當時的做法，廢話不多說，直接上代碼：
在iOS7.0以前，要實現這樣的效果，只有自定義TabBar了，但這很麻煩。而在iOS7.0以后，蘋果在UITabBarControllerDelegate中增加了下面兩個代理方法：
- (nullable id <UIViewControllerInteractiveTransitioning>)tabBarController:(UITabBarController *)tabBarController interactionControllerForAnimationController: (id<UIViewControllerAnimatedTransitioning>)animationController；
- (nullable id <UIViewControllerAnimatedTransitioning>)tabBarController:(UITabBarController *)tabBarController animationControllerForTransitionFromViewController:(UIViewController *)fromVC toViewController:(UIViewController *)toVC；
自定義的滑動代理，在此實現tabbarViewController的兩個新添加的滑動的代理方法
// ScrollTabBarDelegate.h
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
@interface ScrollTabBarDelegate : NSObject <UITabBarControllerDelegate>
@property (nonatomic, assign) BOOL interactive;
@property (nonatomic, strong) UIPercentDrivenInteractiveTransition *interactionController;
@end
//
// ScrollTabBarDelegate.m
#import "ScrollTabBarDelegate.h"
#import "ScrollTabBarAnimator.h"
@interface ScrollTabBarDelegate ()
@property (nonatomic, strong) ScrollTabBarAnimator *tabBarAnimator;
@end
@implementation ScrollTabBarDelegate
- (instancetype)init {
if (self = [super init]) {
_interactive = NO;
_interactionController = [[UIPercentDrivenInteractiveTransition alloc] init];
_tabBarAnimator = [[ScrollTabBarAnimator alloc] init];
}
return self;
}
- (nullable id <UIViewControllerInteractiveTransitioning>)tabBarController:(UITabBarController *)tabBarController
interactionControllerForAnimationController: (id <UIViewControllerAnimatedTransitioning>)animationController {
return self.interactive ? self.interactionController : nil;
}
- (nullable id <UIViewControllerAnimatedTransitioning>)tabBarController:(UITabBarController *)tabBarController
animationControllerForTransitionFromViewController:(UIViewController *)fromVC
toViewController:(UIViewController *)toVC {
NSInteger fromIndex = [tabBarController.viewControllers indexOfObject:fromVC];
NSInteger toIndex = [tabBarController.viewControllers indexOfObject:toVC];
self.tabBarAnimator.tabScrollDirection = (toIndex < fromIndex) ? TabLeftDirection: TabRightDirection;
return self.tabBarAnimator;
}
@end
在自定義一個動畫的類，實現滑動切換tabbar時加載動畫效果：
// ScrollTabBarAnimator.h
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
typedef NS_ENUM(NSInteger,TabOperationDirection) {
TabLeftDirection,
TabRightDirection
};
@interface ScrollTabBarAnimator : NSObject <UIViewControllerAnimatedTransitioning>
@property (nonatomic, assign) TabOperationDirection tabScrollDirection;
@end
// ScrollTabBarAnimator.m
#import "ScrollTabBarAnimator.h"
@implementation ScrollTabBarAnimator
//動畫持續時間
- (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext {
return 0.3;
}
//動畫執行效果
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext {
// 獲取 toView fromView
UIViewController* toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
UIViewController* fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
UIView *containerView = [transitionContext containerView];
if (!toViewController || !fromViewController || !containerView) return;
// 給 toView fromView 設定相應的值
toViewController.view.transform = CGAffineTransformIdentity;
fromViewController.view.transform = CGAffineTransformIdentity;
CGFloat translation = containerView.frame.size.width;
switch (self.tabScrollDirection) {
case TabLeftDirection:
translation = translation;
break;
case TabRightDirection:
translation = -translation;
break;
default:
break;
}
[containerView addSubview:toViewController.view];
toViewController.view.transform = CGAffineTransformMakeTranslation(-translation, 0);
// 真正的變化
[UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{
fromViewController.view.transform = CGAffineTransformMakeTranslation(translation, 0);
toViewController.view.transform = CGAffineTransformIdentity;
} completion:^(BOOL finished) {
fromViewController.view.transform = CGAffineTransformIdentity;
toViewController.view.transform = CGAffineTransformIdentity;
[transitionContext completeTransition:![transitionContext transitionWasCancelled]];
}];
}
@end
在 TabBarController.m 中 實現的方法
導入 ScrollTabBarDelegate 的頭文件后，聲明兩個對象
@property (nonatomic, assign) NSInteger subViewControllerCount;
@property (nonatomic, strong) ScrollTabBarDelegate *tabBarDelegate;
- (void)viewDidLoad {
[super viewDidLoad];
#pragma mark tabbar滑動切換手勢
// 正確的給予 count
self.subViewControllerCount = self.viewControllers ? self.viewControllers.count : 0;
設置 tabbarViewController 的代理為 ScrollTabBarDelegate ，並給 tabbarViewController 的view添加滑動手勢
// 代理
self.tabBarDelegate = [[ScrollTabBarDelegate alloc] init];
self.delegate = self.tabBarDelegate;
// 增加滑動手勢
self.panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panHandle:)];
[self.view addGestureRecognizer:self.panGesture];
}
實現滑動手勢，切換tabbarViewController的item到不同的控制器
- (void)panHandle:(UIPanGestureRecognizer *)panGesture {
// 獲取滑動點
CGFloat translationX = [panGesture translationInView:self.view].x;
CGFloat progress = fabs(translationX)/self.view.frame.size.width;
switch (panGesture.state) {
case UIGestureRecognizerStateBegan:
{
self.tabBarDelegate.interactive = YES;
CGFloat velocityX = [panGesture velocityInView:self.view].x;
if (velocityX < 0) {
if (self.selectedIndex < self.subViewControllerCount - 1) {
self.selectedIndex += 1;
}
}
else {
if (self.selectedIndex > 0) {
self.selectedIndex -= 1;
}
}
}
break;
case UIGestureRecognizerStateChanged:
{
[self.tabBarDelegate.interactionController updateInteractiveTransition:progress];
}
break;
case UIGestureRecognizerStateEnded:
case UIGestureRecognizerStateFailed:
case UIGestureRecognizerStateCancelled:
{
if (progress > 0.3) {
self.tabBarDelegate.interactionController.completionSpeed = 0.99;
[self.tabBarDelegate.interactionController finishInteractiveTransition];
}else{
//轉場取消后，UITabBarController 自動恢復了 selectedIndex 的值，不需要我們手動恢復。
self.tabBarDelegate.interactionController.completionSpeed = 0.99;
[self.tabBarDelegate.interactionController cancelInteractiveTransition];
}
self.tabBarDelegate.interactive = NO;
}
break;
default:
break;
}
}
這樣實現以后，會出現一個問題，就是當跳轉到子控制器的時候，子控制器也可以滑動，這就不對了，於是果斷的開始查找原因，發現所有的控制器的
rootViewController 都是 tabbarViewController，所以需要在跳轉的時候吧 tabbarViewController 的view的滑動手勢給移除掉，當返回來的時候再給加上去，於是把 UIPanGestureRecognizer 的對象在tabbarViewController.h 中搞成一個全局對象
@property (nonatomic, strong) UIPanGestureRecognizer *panGesture;
在自定義的 UINavigationController 中，重寫 pushViewController 方法，在此方法中移除tabbarViewController 的view的滑動手勢，代碼如下：
- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated {
if (self.viewControllers.count > 0) {
viewController.hidesBottomBarWhenPushed = YES;
// 跳轉后移除滑動手勢
[[UIApplication sharedApplication].delegate.window.rootViewController.view removeGestureRecognizer:viewController.cyl_tabBarController.panGesture];
注冊一個通知，通知在第一層的控制器吧tabbarViewController 的view的滑動手勢給添加上去
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(scrollNextViewController) name:@"SCROLLTABBARCONTROLLER" object:nil]；
}
[super pushViewController:viewController animated:animated];
}
當返回到第一層的控制器的時候，在返回按鈕點擊的時候發布一個通知，通知在第一層的控制器吧tabbarViewController 的view的滑動手勢給添加上去
-(void)scrollNextViewController {
if (self.childViewControllers.count == 1 && [(AppDelegate *)[UIApplication sharedApplication].delegate isBackBtn] == YES) {
// 返回后重新添加滑動手勢
[[UIApplication sharedApplication].delegate.window.rootViewController.view addGestureRecognizer:[UIApplication sharedApplication].delegate.window.rootViewController.cyl_tabBarController.panGesture];
}
}
結束后別忘了移除通知
- (void)dealloc {
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
到此處，關於tabbarViewController的左右滑動切換的問題算是解決了。