自定义视图控制器转场
参考
- GitHub 源码：shinobicontrols/iOS7-day-by-day
- 天天品尝iOS7甜点 :: Day 10 :: Custom UIViewController Transitions
转场效果
默认的 UINavigationController 转场 push/pop 是这样的：
现在我们要实现自定义实现视图控制器转场效果：
视图层次结构
视图层次结构很简单：一个 UINavigationController 作为窗口的根视图控制器、而首页是 UINavigationController 的根视图控制器、首页可以 push 到第二页：
要想实现自定义视图控制器转场效果，需要实现 UINavigationControllerDelegate 协议。
在 UINavigationController 实例对象中声明某个类（HQLNavControllerDelegate）实现了UINavigationControllerDelegate 协议：
#import "HQLNavigationController.h"
#import "HQLNavControllerDelegate.h"
@interface HQLNavigationController () {
id<UINavigationControllerDelegate> _navDelegate;
}
@end
@implementation HQLNavigationController
- (instancetype)initWithCoder:(NSCoder *)aDecoder {
self = [super initWithCoder:aDecoder];
if (self) {
_navDelegate = [HQLNavControllerDelegate new];
self.delegate = _navDelegate;
}
return self;
}
上面代码中把实现转场效果的协议方法封装成了一个类HQLNavControllerDelegate：
// ****************************************************
// HQLNavControllerDelegate.h
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
@interface HQLNavControllerDelegate : NSObject <UINavigationControllerDelegate>
@end
// ****************************************************
// HQLNavControllerDelegate.m
#import "HQLNavControllerDelegate.h"
#import "HQLFadeTransition.h"
@implementation HQLNavControllerDelegate
- (nullable id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController
animationControllerForOperation:(UINavigationControllerOperation)operation
fromViewController:(UIViewController *)fromVC
toViewController:(UIViewController *)toVC{
return [HQLFadeTransition new];
}
@end
而在 HQLNavControllerDelegate 类中又把实现自定义转场效果的转场动画封装成了一个类 HQLFadeTransition
// ****************************************************
// HQLFadeTransition.h
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
@interface HQLFadeTransition : NSObject <UIViewControllerAnimatedTransitioning>
@end
// ****************************************************
// HQLFadeTransition.m
#import "HQLFadeTransition.h"
@implementation HQLFadeTransition
// @required 方法：返回动画的时长
- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext {
return 2.0;
}
// @required 方法：实现视图控制器之间的转场效果
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext {
// 1️⃣ viewControllerForKey:获取与转场相关的两个视图控制器
// UITransitionContextFromViewControllerKey
UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
// UITransitionContextToViewControllerKey
UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
// 2️⃣ containerView - 动画发生的容器视图
UIView *containerView = [transitionContext containerView];
// 3️⃣ 将两个视图控制器的子视图添加到容器视图
[containerView addSubview:fromVC.view];
[containerView addSubview:toVC.view];
// 4️⃣ 将要转换到的那个视图设置为透明
toVC.view.alpha = 0.0;
// 5️⃣ 执行动画
[UIView animateWithDuration:[self transitionDuration:transitionContext]
delay:0
options:0
animations:^{
// 动画效果
toVC.view.alpha = 1.f;
}
completion:^(BOOL finished) {
// 移除旧视图控制器视图
[fromVC.view removeFromSuperview];
// 告诉 transitionContext 上下文，动画完成啦!
[transitionContext completeTransition:YES];
}];
}
// 转换完成后调用
- (void)animationEnded:(BOOL) transitionCompleted {
NSLog(@"Transition Completed!");
}
@end
The end.
