presentViewController之系统动画

东西多了，脑子不够存，当需要的时候，总是觉得好像知道，却又不是真的知道，去找资料，看文档都是在浪费时间。那就清理一下脑存吧。方便以后用。

present动画.gif

• 在UIViewController.h中有这样一个枚举

typedef NS_ENUM(NSInteger, UIModalTransitionStyle) {
    UIModalTransitionStyleCoverVertical = 0,
    UIModalTransitionStyleFlipHorizontal __TVOS_PROHIBITED,
    UIModalTransitionStyleCrossDissolve,
    UIModalTransitionStylePartialCurl NS_ENUM_AVAILABLE_IOS(3_2) __TVOS_PROHIBITED,
};

• 效果图上按钮依次对应的方法

//UIModalTransitionStyleCoverVertical
- (IBAction)coverVertical:(id)sender {
    BViewController *bvc = [[BViewController alloc] init];
    
    bvc.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
    
    [self presentViewController:bvc animated:YES completion:nil];
    
}

//UIModalTransitionStyleFlipHorizontal
- (IBAction)flipHorizontal:(id)sender {
    BViewController *bvc = [[BViewController alloc] init];
    
    bvc.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
    
    [self presentViewController:bvc animated:YES completion:nil];
}

//UIModalTransitionStyleCrossDissolve
- (IBAction)crossDissolve:(id)sender {
    BViewController *bvc = [[BViewController alloc] init];
    
    bvc.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
    
    [self presentViewController:bvc animated:YES completion:nil];
}

//UIModalTransitionStylePartialCurl
- (IBAction)partialCurl:(id)sender {
    BViewController *bvc = [[BViewController alloc] init];
    
    bvc.modalTransitionStyle = UIModalTransitionStylePartialCurl;
    
    [self presentViewController:bvc animated:YES completion:nil];
}

• 有前进就有后退

  从A控制器present到B再到C控制器，现在想要从C直接回到A，怎么办呢？首先需要知道的是：A 是 B的presentingViewController，B 是 A的presentedViewController，同样B 是 C的presentingViewController，C 是 B的presentedViewController。这样就能很好的理解每一次的present，前后控制器都有关联的，后退也就简单了。代码如下：

- (void)gobackAction {
    UIViewController *rootVC = self.presentingViewController;
    UIViewController *bottomVC;
    while (rootVC) {
        bottomVC = rootVC;
        rootVC = rootVC.presentingViewController;
        
        NSLog(@"有:%s,%s",object_getClassName(bottomVC),object_getClassName(rootVC));
    }
    [bottomVC dismissViewControllerAnimated:YES completion:nil];
    
}