GMPresentAnimation 初步成型，但是还需要拆分

GMBase/Classes/GMPresentAnimation.h

@@ -8,6 +8,7 @@
 
 #import <Foundation/Foundation.h>
 
-@interface GMPresentAnimation : NSObject<UIViewControllerAnimatedTransitioning>
-@property(nonatomic,assign)UINavigationControllerOperation transitionType;
+// 通过使用GMPresentAnimation，来自定义 push 动画
+@interface GMPresentAnimation : NSObject <UIViewControllerAnimatedTransitioning>
+@property(nonatomic, assign) UINavigationControllerOperation transitionType;
 @end

GMBase/Classes/GMPresentAnimation.m

@@ -8,7 +8,7 @@
 
 #import "GMPresentAnimation.h"
 #import "UIViewController+PushType.h"
-@interface GMPresentAnimation() <UIViewControllerAnimatedTransitioning>
+@interface GMPresentAnimation ()
 @property(nonatomic, assign) NSTimeInterval duration;
 @end
 @implementation GMPresentAnimation
@@ -16,91 +16,74 @@
 - (instancetype)init {
     // 默认 push 动画时间0.6
     if (self = [super init]) {
-        self.duration = 0.6;
+        self.duration = 0.3;
     }
     return self;
 }
 
-- (void)push:(id<UIViewControllerContextTransitioning>)transitionContext
-{
-    UIViewController *fromVC    = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
-    UIViewController *toVC      = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
-    NSTimeInterval duration     = [self transitionDuration:transitionContext];
-    
-    CGRect bound                = [[UIScreen mainScreen] bounds];
-    fromVC.view.hidden          = YES;
+- (void)push:(id<UIViewControllerContextTransitioning>)transitionContext {
+    CGRect bounds = [[UIScreen mainScreen] bounds];
+    UIView *fromView = [transitionContext viewForKey:UITransitionContextFromViewKey];
+    UIView *toView = [transitionContext viewForKey:UITransitionContextToViewKey];
 
+    // 在containerView上加一个toVC.snapshot，把之前页面当作背景
+    // 不加的话，toView在动画结束时会被系统移除，进而底部背景会突然变白
+    UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
+    fromVC.snapshot.frame = bounds;
     [[transitionContext containerView] addSubview:fromVC.snapshot];
-    [[transitionContext containerView] addSubview:toVC.view];
     
-    [[toVC.navigationController.view superview] insertSubview:fromVC.snapshot belowSubview:toVC.navigationController.view];
-    
-    toVC.navigationController.view.layer.anchorPoint = CGPointMake(0.5, 2.0);
-    toVC.navigationController.view.frame = bound;
-    
-    toVC.navigationController.view.transform = CGAffineTransformMakeTranslation(0, CGRectGetHeight(bound));
-    
-    [UIView animateWithDuration:duration
-                          delay:0
-         usingSpringWithDamping:1.0
-          initialSpringVelocity:0
-                        options:UIViewAnimationOptionCurveEaseInOut
-                     animations:^{
-                        fromVC.snapshot.transform = CGAffineTransformMakeTranslation(0, 0);
-                        toVC.navigationController.view.transform = CGAffineTransformMakeTranslation(0, 0);
-                     }
-                     completion:^(BOOL finished) {
-                        fromVC.view.hidden = NO;
+    // 添加一个半透明的蒙层，展示在 from view 下面
+    UIView *mask = [[UIView alloc] initWithFrame:bounds];
+    mask.backgroundColor = [UIColor colorWithWhite:0 alpha:0.64];
+    mask.alpha = 0;
+    mask.tag = 100;
+    [[transitionContext containerView] addSubview:mask];
+
+    // 系统不会为我们自动添加 toView，所以我们需要自己添加，以保证 toView 的页面及动画正常展示
+    [[transitionContext containerView] addSubview:toView];
+
+    // 先将toView放置在屏幕下边，为下一步的平移动画做准备
+    CGRect newFrame = toView.frame;
+    newFrame.origin.y = CGRectGetHeight(bounds);
+    toView.frame = newFrame;
+
+    // 从下到上的平移动画
+    [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{
+        toView.frame = bounds;
+        mask.alpha = 1;
+    } completion:^(BOOL finished) {
         [transitionContext completeTransition:YES];
     }];
 }
 
 
 - (void)pop:(id<UIViewControllerContextTransitioning>)transitionContext {
-    
-    UIViewController * fromVC  = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
-    UIViewController * toVC         = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
-    NSTimeInterval duration         = [self transitionDuration:transitionContext];
     CGRect bound = [[UIScreen mainScreen] bounds];
+    UIView *fromView = [transitionContext viewForKey:UITransitionContextFromViewKey];;
+    UIView *toView = [transitionContext viewForKey:UITransitionContextToViewKey];
 
-    [fromVC.view addSubview:fromVC.snapshot];
-    fromVC.navigationController.navigationBar.hidden = YES;
-    
-    // 添加阴影
-    fromVC.snapshot.layer.shadowColor = [UIColor colorWithRed:0.2 green:0.2 blue:0.2 alpha:0.8].CGColor;
-    fromVC.snapshot.layer.shadowOffset = CGSizeMake(-3, 0);
-    fromVC.snapshot.layer.shadowOpacity = 0.5;
+    // 必须把先前的 mask view 拿出来，显示的标记为 alpha = 1，要不然会发现该蒙层是突然消失
+    // 经常打断点发现，其 alpha 此时为0，所以必须要设置一下 alpha = 1
+    [[transitionContext containerView] viewWithTag:100].alpha = 1;
 
-    fromVC.view.layer.anchorPoint = CGPointMake(0.5, 2.5);
-    fromVC.view.frame = bound;
-
-    toVC.view.hidden = YES;
-    
-    [[transitionContext containerView] addSubview:toVC.view];
-    [[transitionContext containerView] addSubview:toVC.snapshot];
-    [[transitionContext containerView] sendSubviewToBack:toVC.snapshot];
-
-    [UIView animateWithDuration:duration
-                          delay:0
-         usingSpringWithDamping:1.0
-          initialSpringVelocity:0
-                        options:UIViewAnimationOptionCurveEaseInOut
-                     animations:^{
-                        fromVC.view.transform = CGAffineTransformMakeTranslation(0,  CGRectGetHeight(bound));
-                        toVC.snapshot.alpha = 1;
-
-                     }
-                     completion:^(BOOL finished) {
-                        toVC.navigationController.navigationBar.hidden = NO;
-                        toVC.view.hidden = NO;
-                         
-                        [fromVC.snapshot removeFromSuperview];
+    //将toView加到toVC.snapshot 的的下面。
+    // 不加的话，动画结束后看不到 toView
+    // 动画过程中看到的是toVC.snapshot
+    // 并且需要将 toView放到toVC.snapshot的下面，确保view层级正确
+    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
+    [[transitionContext containerView] insertSubview:toView belowSubview:toVC.snapshot];
+
+    CGRect newFrame = fromView.frame;
+    newFrame.origin.y = CGRectGetHeight(bound);
+    [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{
+        fromView.frame = newFrame;
+        [[transitionContext containerView] viewWithTag:100].alpha = 0;
+    } completion:^(BOOL finished) {
+        [[[transitionContext containerView] viewWithTag:100] removeFromSuperview];
+        // 动画结束后移除toVC.snapshot，留着会挡住toVC，用户无法交互
         [toVC.snapshot removeFromSuperview];
-                         
-                        if (![transitionContext transitionWasCancelled])
-                        {
+        // 需要将toVC.snapshot清空，下一次弹窗时再重新生成 snapshot，确保每一次 snapshot 为最新画面
         toVC.snapshot = nil;
-                        }
         [transitionContext completeTransition:![transitionContext transitionWasCancelled]];
      }];
 }
@@ -110,14 +93,10 @@
     return self.duration;
 }
 
-- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext
-{
-    if (self.transitionType == UINavigationControllerOperationPush)
-    {
+- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext {
+    if (self.transitionType == UINavigationControllerOperationPush) {
         [self push:transitionContext];
-    }
-    else if (self.transitionType == UINavigationControllerOperationPop)
-    {
+    } else if (self.transitionType == UINavigationControllerOperationPop) {
         [self pop:transitionContext];
     }
 }