CoreAnimation：将动画对象转移到下一个 UIViewController

Question

我目前正在使用这个核心动画； （iOS 5，ARC）

- (void)onTimer
{
    // build a view from our image
    UIImageView* flakeView = [[UIImageView alloc] initWithImage:flakeImage];

    // use the random() function to randomize up our flake attributes
    int startX = round(random() % 320);
    int endX = startX; //round(random() % 320);
    double scale = 1 / round(random() % 100) + 1.0;
    double speed = 1 / round(random() % 100) + 1.0;

    // set the flake start position
    flakeView.frame = CGRectMake(startX, -100.0, 25.0 * scale, 25.0 * scale);
    flakeView.alpha = 0.8;

    // put the flake in our main view
    [self.view addSubview:flakeView];
    [self.view sendSubviewToBack:flakeView];

    [UIView beginAnimations:nil context:(__bridge void*)flakeView];
    // set up how fast the flake will fall
    [UIView setAnimationDuration:10 * speed];

    // set the postion where flake will move to
    flakeView.frame = CGRectMake(endX, 500.0, 25.0 * scale, 25.0 * scale);

    // set a stop callback so we can cleanup the flake when it reaches the
    // end of its animation
    [UIView setAnimationDidStopSelector:@selector(onAnimationComplete:finished:context:)];
    [UIView setAnimationDelegate:self];
    [UIView commitAnimations];

}
- (void)onAnimationComplete:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context {

    UIImageView *flakeView = (__bridge UIImageView*)context;
    [flakeView removeFromSuperview];
    flakeView = nil;
}

火;

[NSTimer scheduledTimerWithTimeInterval:(0.3) target:self selector:@selector(onTimer) userInfo:nil repeats:YES];

使用此代码，有 10 片雪花出现，落下。

借助此代码和一些自定义视图转换，我试图使导航操作流畅。问题是我找不到将这些（动画）上下文转移到下一个 UIViewController 的正确方法，因此所有动画雪花将继续从它们离开的地方继续，而下一个 UIViewController 的 NSTimer 将触发新的那些。

任何帮助和建议都将得到应用。

Answer 1

也许您可以将您的上下文放在此类的私有扩展中。
点赞：@property (nonatomic,weak)IBOutlet UIImageView*context;

Answer 2

我怀疑您是否可以将正在制作动画的视图转移到另一个视图控制器。我怀疑当你从它的超级视图中删除它时，它会终止任何动画。

您最好编写代码来跟踪在数组中动画的视图。当需要创建一个新的视图控制器时，查询每个图像视图层的presentationLayer并获取它的位置。然后从当前视图控制器中删除所有雪花视图，并将整个数组以及位置数组传递给新的视图控制器。然后在新视图控制器的 viewDidLoad 中，在它们之前的位置添加雪花视图数组，并开始动画到它们之前的结束位置，并启动动画计时器以开始添加更多雪花。

Answer 3

.h 文件

@interface BeanManager : NSObject <UINavigationControllerDelegate>
{
    NSMutableDictionary *beanDictionary;
    UIViewController    *currentViewController;
    UIImage             *coffeebean;
    NSTimer             *beanTimer;
    NSInteger           contextTag;
    BOOL                isDebugging;
}

@property (nonatomic, retain) NSMutableDictionary   *beanDictionary;
@property (nonatomic, retain) UIViewController      *currentViewController;
@property (nonatomic) BOOL isDebugging;

+ (id)sharedManager;

- (void)invalidate;
- (void)validate;

@end

.m 文件

+ (id)sharedManager {
    static BeanManager *sharedMyManager = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        sharedMyManager = [[self alloc] init];
    });
    return sharedMyManager;
}

- (id)init {
    if (self = [super init]) {
        coffeebean = [UIImage imageNamed:@"coffeebean"];

        // assign self as navigation controllers delegate
        AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
        [appDelegate.navigationController setDelegate:self];

        self.currentViewController = appDelegate.navigationController.visibleViewController;

        beanDictionary = [[NSMutableDictionary alloc] init];

        NSLog(@"%@ : Allocating",[self class]);

        [self validate];
    }
    return self;
}

- (void)dealloc {
    if (isDebugging) {
        NSLog(@"%@: Deallocating", [self class]);
    }
}

#pragma mark - UINavigationController
- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    if (isDebugging) {
        NSLog(@"%@: Pushing %d beans to new view",[self class], [[beanDictionary allKeys] count]);
    }
    for (UIImageView *animatingBeans in [beanDictionary allValues]) {
        [viewController.view addSubview:animatingBeans];
        [viewController.view sendSubviewToBack:animatingBeans];
    }

    self.currentViewController = viewController;
}

#pragma mark - Internals
- (void)validate
{
    beanTimer = [NSTimer scheduledTimerWithTimeInterval:(0.3) target:self selector:@selector(onTimerWithBlock) userInfo:nil repeats:YES];
}

- (void)invalidate
{
    [beanTimer invalidate];
}

- (void)onTimerWithBlock
{
    // build a view from our flake image
    UIImageView* beanView = [[UIImageView alloc] initWithImage:coffeebean];

    // use the random() function to randomize up our flake attributes
    int startX = round(random() % 320);
    int endX = startX; //round(random() % 320);
    double scale = 1 / round(random() % 100) + 1.0;
    double speed = 1 / round(random() % 100) + 1.0;

    // set the flake start position
    beanView.frame = CGRectMake(startX, -100.0, 25.0 * scale, 25.0 * scale);
    beanView.alpha = 0.8;
    beanView.tag = contextTag; 

    [beanDictionary setObject:beanView forKey:[NSString stringWithFormat:@"%d",contextTag]];

    if (contextTag > 1000) {
        contextTag = 0;
    }
    contextTag++;

    // put the flake in our main view
    [self.currentViewController.view addSubview:beanView];
    [self.currentViewController.view sendSubviewToBack:beanView];

    [UIView animateWithDuration:(speed * 10) animations:^{

        [beanView setFrame:CGRectMake(endX, 500.0, 25.0 * scale, 25.0 * scale)];

    } completion:^(BOOL finished) 
    {
        [beanDictionary removeObjectForKey:[NSString stringWithFormat:@"%d",beanView.tag]];
        if (isDebugging) {
            NSLog(@"%@: Dictionary Count %d",[self class], [[beanDictionary allKeys] count]);
        }
        [beanView removeFromSuperview];
    }];
}

这段代码似乎完成了这项工作。到目前为止，我没有将它用作单例，但如果我将扩展此代码，它应该作为单例实现，只是为了澄清。而且我使用的是NSDictionary 而不是NSArray，它可以按原样工作，我再次认为我可能会为其添加一些功能，所以我将其设为NSDictionary