CoreAnimation: Transferring animating objects to next UIViewController - iphone

Question

I am currently using this core animation; (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;
}
fire;
[NSTimer scheduledTimerWithTimeInterval:(0.3) target:self selector:#selector(onTimer) userInfo:nil repeats:YES];
With this code, there are 10s of snow flakes are presented, falling down.
With the help of this code, and some custom view transitions, I am trying to make navigation actions fluid. The problem is I cannot find the proper way to transfer these (animating) context to the next UIViewController so all the animating snow flakes will keep on going where they left, and the next UIViewController's NSTimer will fire new ones.
Any help and suggestions will be appriciated.

Answer 1

Maybe you can put your context in your private extension of this class.
Like:#property (nonatomic,weak)IBOutlet UIImageView*context;

Answer 2

I doubt if you can transfer a view that is animating to another view controller. I suspect that when you remove it from its superview, it will terminate any animations.
You would probably be better off writing code that keeps track of the views that are animating in an array. When it's time to create a new view controller, query the presentationLayer of each image view's layer and get it's position. Then remove all the snowflake views from the current view controller and pass the whole array, plus an array of positions, to the new view controller. Then in the new view controller's viewDidLoad, add the array of snowflake views at their previous positions and start them animating to their previous end positions, and start an animation timer to begin adding more snowflakes.

Answer 3

.h file
#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 file
+ (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];
}];
}
This code seemed to do the work. Just far, I am not using it as a Singleton, but if I will expand this code, it should be implemented as a singleton, just to clarify. And I am using an NSDictionary instead of an NSArray which would work just as is, again I considered I might add some features to it, so I made it an NSDictionary