我正在尝试在我的viewcontroller上实现SwipeGesture。
我目前面临的问题是我无法确定当前显示的子视图控制器是什么。
swipeGesture被添加到容器视图控制器中。然后必须确定父子关系中当前显示的VC是什么，然后向右或向左移动。
答案 0 :(得分：5)
如果您正在谈论自定义容器视图控制器，那么容器控制器的工作就是跟踪它。因此，您可能拥有自己的@property，可以跟踪您所在的transitionFromController，并在滑动后按transitionFromViewController进行调整。所以你可能有一个数字属性，当你向右移动时你会递增，而当你向左移动时，你会递减。
一般情况下（如果您只是想跟踪哪个“来自”控制器，您传递给viewDidLoad），有两种方法。清单14-3在 View Controller Programming Guide的Adding a child controller中列出了一种方法。
在这种情况下，在addChildViewController中，您为第一个视图控制器执行addChildViewController。在这种情况下，您不会在此时通过[self.childViewControllers lastObject]加载其他子视图控制器，而是让您执行转换的方法处理该问题（如清单14-3所示）。 / p>
如果你这样做，你可以抓住@interface ViewController ()
@property (nonatomic) NSInteger currentIndex;
@end
@implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
UIViewController *initialController = ... // set your initial controller
[self addChildViewController:initialController];
initialController.view.frame = self.containerView.bounds;
[self.containerView addSubview:initialController.view];
[initialController didMoveToParentViewController:self];
UISwipeGestureRecognizer *gesture;
gesture = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipe:)];
gesture.direction = UISwipeGestureRecognizerDirectionRight;
[self.containerView addGestureRecognizer:gesture];
gesture = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipe:)];
gesture.direction = UISwipeGestureRecognizerDirectionLeft;
[self.containerView addGestureRecognizer:gesture];
}
- (void) handleSwipe:(UISwipeGestureRecognizer *)gesture
{
if (gesture.direction == UISwipeGestureRecognizerDirectionLeft && self.currentIndex < (kMaxIndex - 1))
{
self.currentIndex++;
UIViewController *newController = ... // set your new controller
UIViewController *oldController = [self.childViewControllers lastObject];
[self cycleFromViewController:oldController
toViewController:newController
direction:gesture.direction];
}
else if (gesture.direction == UISwipeGestureRecognizerDirectionRight && self.currentIndex > 0)
{
self.currentIndex--;
UIViewController *newController = ... // set your new controller
UIViewController *oldController = [self.childViewControllers lastObject];
[self cycleFromViewController:oldController
toViewController:newController
direction:gesture.direction];
}
}
- (void) cycleFromViewController:(UIViewController*) oldController
toViewController:(UIViewController*) newController
direction:(UISwipeGestureRecognizerDirection)direction
{
[oldController willMoveToParentViewController:nil];
[self addChildViewController:newController];
newController.view.frame = oldController.view.frame;
UIViewAnimationOptions options;
if (direction == UISwipeGestureRecognizerDirectionRight)
options = UIViewAnimationOptionTransitionFlipFromLeft;
else if (direction == UISwipeGestureRecognizerDirectionLeft)
options = UIViewAnimationOptionTransitionFlipFromRight;
[self transitionFromViewController:oldController
toViewController:newController
duration:0.33
options:options
animations:^{
[oldController removeFromParentViewController];
}
completion:^(BOOL finished) {
[newController didMoveToParentViewController:self];
}];
}
，这将是你的“当前”子控制器。所以，这可能看起来像：
addChildViewController我见过的其他模型是通过viewDidLoad中的childViewControllers加载所有潜在的子控制器。我个人并不喜欢这种方法，但我知道人们这样做，而且效果很好。
但如果你这样做，你就不能再依赖currentChildController来知道哪个控制器是当前控制器。在这种情况下，您必须为@interface ViewController ()
@property (nonatomic, strong) UIViewController *currentChildController;
@property (nonatomic) NSInteger currentIndex;
@end
@implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
[self addChildViewController:[self.storyboard instantiateViewControllerWithIdentifier:@"ChildOne"]];
[self addChildViewController:[self.storyboard instantiateViewControllerWithIdentifier:@"ChildTwo"]];
[self addChildViewController:[self.storyboard instantiateViewControllerWithIdentifier:@"ChildThree"]];
self.currentChildController = self.childViewControllers[0];
self.currentChildController.view.frame = self.containerView.bounds;
[self.containerView addSubview:self.currentChildController.view];
for (UIViewController *controller in self.childViewControllers)
[controller didMoveToParentViewController:self];
UISwipeGestureRecognizer *gesture;
gesture = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipe:)];
gesture.direction = UISwipeGestureRecognizerDirectionRight;
[self.containerView addGestureRecognizer:gesture];
gesture = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipe:)];
gesture.direction = UISwipeGestureRecognizerDirectionLeft;
[self.containerView addGestureRecognizer:gesture];
}
- (void) cycleFromViewController:(UIViewController*) oldController
toViewController:(UIViewController*) newController
direction:(UISwipeGestureRecognizerDirection) direction
{
self.currentChildController = newController;
newController.view.frame = oldController.view.frame;
UIViewAnimationOptions options;
if (direction == UISwipeGestureRecognizerDirectionRight)
options = UIViewAnimationOptionTransitionFlipFromLeft;
else if (direction == UISwipeGestureRecognizerDirectionLeft)
options = UIViewAnimationOptionTransitionFlipFromRight;
[self transitionFromViewController:oldController
toViewController:newController
duration:0.33
options:options
animations:^{
}
completion:nil];
}
- (void) handleSwipe:(UISwipeGestureRecognizer *)gesture
{
if (gesture.direction == UISwipeGestureRecognizerDirectionLeft && self.currentIndex < (kMaxIndex - 1))
{
self.currentIndex++;
UIViewController *oldController = self.currentChildController;
UIViewController *newController = self.childViewControllers[self.currentIndex];
[self cycleFromViewController:oldController
toViewController:newController
direction:gesture.direction];
}
else if (gesture.direction == UISwipeGestureRecognizerDirectionRight && self.currentIndex > 0)
{
self.currentIndex--;
UIViewController *oldController = self.currentChildController;
UIViewController *newController = self.childViewControllers[self.currentIndex];
[self cycleFromViewController:oldController
toViewController:newController
direction:gesture.direction];
}
}
定义自己的类属性。所以它可能看起来像：
[self.childViewControllers lastObject]这是两种合乎逻辑的方法。
顺便说一下，第一种方法并不排除拥有自己的类属性来知道你所使用的控制器，有时这很有用（例如，如果你使用的动画类型取决于你是否会去“正确”或“左”，但除非是这种情况，否则只需看{{1}}即可逃脱。
答案 1 :(得分：0)
在我正在进行的项目中，我有许多View Controller，每个都有自己的导航控制器添加到父视图控制器。我知道最初的入学孩子，但我会做以下事情来找到孩子当前显示的孩子：
[myKnownViewController.childViewControllers objectAtIndex:0].navigationController.topViewController