Transisition 动画，多种思路

思路一: Transisition 动画 ， 点击哪里，从那里弹出，铺满屏幕，

取代 Ctrl 的modal 模态 和 Navigation Ctrl 的 push 界面

照片 浏览器的 ， DSImageShowView 的 两个 方法

法子挺笨的。都不是 Ctrl 层的。 在原Ctrl 的view 上添加 view.
通过 convertRect: toView: 获取坐标， 再 用 UIView 的 动画，来 呈现 Transition.
起码也要用 嵌套 视图 控制器嘛。

- (void)presentfromImageView:(UIView *)fromView toContainer:(UIView *)toContainer index:(NSInteger)index animated:(BOOL)animated completion:(void (^)(void))completion {
  
    _fromView = fromView;
    _toContainerView = toContainer;
    NSInteger page = 0;

    page = index;
    if (index < 0 || index > 8) page = 0;
    
    _hiddenView = fromView;
    _hiddenView.hidden = YES;

    
    UIBlurEffect *blurEffect = [UIBlurEffect effectWithStyle: UIBlurEffectStyleLight ];
    UIVisualEffectView *effectView = [[UIVisualEffectView alloc] initWithEffect:blurEffect];
    effectView.frame = _blurBackground.bounds;
    [_blurBackground addSubview:effectView];

    
    self.size = _toContainerView.size;
    self.blurBackground.alpha = 0;
    self.pager.numberOfPages = self.items.count;
    self.pager.currentPage = page;
    [_toContainerView addSubview: self];
    
    _scrollView.contentSize = CGSizeMake(_scrollView.width * self.items.count, _scrollView.height);
    [_scrollView scrollRectToVisible:CGRectMake(_scrollView.width * page, 0, _scrollView.width, _scrollView.height) animated:NO];
    [self scrollViewDidScroll: _scrollView];
    
    [UIView setAnimationsEnabled:YES];
    NSInteger currentPage = self.currentPage;
    DSImageScrollView *scrollView = [self scrollViewForPage:currentPage];
    DSImageScrollItem *item = _items[currentPage];
    
    if (!item.thumbClippedToTop) {
        NSString *imageKey = [[YYWebImageManager sharedManager] cacheKeyForURL:item.largeImageURL];
        if ([[YYWebImageManager sharedManager].cache getImageForKey:imageKey withType:YYImageCacheTypeMemory]) {
            scrollView.item = item;
        }
    }
    
    if (!scrollView.item) {
        scrollView.imageView.image = item.thumbImage;
        [scrollView resizeSubviewSize];
    }
    
    CGRect fromFrame = [_fromView convertRect: _fromView.bounds toView:scrollView.imageContainerView];
    [self presentAnimation:scrollView fromRect:fromFrame completion:^{
        if (completion) completion();
    }];
}

//present animation
- (void)presentAnimation:(DSImageScrollView *)scrollView fromRect:(CGRect)fromFrame completion:(void (^)(void))completion{
    scrollView.imageContainerView.clipsToBounds = NO;
    scrollView.imageView.frame = fromFrame;
    scrollView.imageView.contentMode = UIViewContentModeScaleAspectFill;
    _blurBackground.alpha = 1;
    [UIApplication sharedApplication].keyWindow.windowLevel = UIWindowLevelStatusBar;
    _scrollView.userInteractionEnabled = NO;
    
    [UIView animateWithDuration:0.18 delay:0 options:UIViewAnimationOptionBeginFromCurrentState | UIViewAnimationOptionCurveEaseInOut animations:^{
        scrollView.imageView.frame = scrollView.imageContainerView.bounds;
        scrollView.imageView.layer.transformScale = 1.01;
    }completion:^(BOOL finished) {
        [UIView animateWithDuration:0.18 delay:0 options:UIViewAnimationOptionBeginFromCurrentState|UIViewAnimationOptionCurveEaseInOut animations:^{
            scrollView.imageView.layer.transformScale = 1.0;
            _pager.alpha = 1;
        }completion:^(BOOL finished) {
            scrollView.imageContainerView.clipsToBounds = YES;
            _isPresented = YES;
            [self scrollViewDidScroll:_scrollView];
            _scrollView.userInteractionEnabled = YES;
            if (completion) completion();
        }];
    }];
}