iOS交互式动画转场

iOS交互式动画转场

实现UIPercentDrivenInteractiveTransition

-(void)updateInteractiveTransition:(CGFloat)percentComplete 更新百分比，一般通过手势识别的长度之类的来计算一个值，然后进行更新。

-(void)cancelInteractiveTransition 取消操作，返回切换前的状态
–(void)finishInteractiveTransition 完成操作，更新到切换后的状态

当手势结束，根据手势的状态判断是取消还是完成，调用如下方法
finishInteractiveTransition 或者 cancelInteractiveTransition 方法.

- (void)handlePopRecognizer:(UIScreenEdgePanGestureRecognizer*)recognizer {
    // 计算滑了多远
    CGFloat progress = [recognizer translationInView:self.view].x / (self.view.bounds.size.width * 1.0);
    progress = MIN(1.0, MAX(0.0, progress));

    if (recognizer.state == UIGestureRecognizerStateBegan) {
        // 创建过渡对象，弹出viewController
        self.interactivePopTransition = [[UIPercentDrivenInteractiveTransition alloc] init];
        [self.navigationController popViewControllerAnimated:YES];
    }
    else if (recognizer.state == UIGestureRecognizerStateChanged) {
        // 更新 interactive transition 的进度
        [self.interactivePopTransition updateInteractiveTransition:progress];
    }
    else if (recognizer.state == UIGestureRecognizerStateEnded || recognizer.state == UIGestureRecognizerStateCancelled) {
        // 完成或者取消过渡
        if (progress > 0.5) {
            [self.interactivePopTransition finishInteractiveTransition];
        }
        else {
            [self.interactivePopTransition cancelInteractiveTransition];
        }

        self.interactivePopTransition = nil;
    }

}