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Static variables inside Objective-C blocks?

I am working on some CoreAnimation materials. Navigation controller with multiple controllers. Presentation controllers have UISCrollViews for different brochure "pages". On each page, an animation may appear that fires when the user flips to this page.

I tried something like this (for one-time animations).

void (^animationBlock)() =
  ^{
    static bool alreadyTriggered = NO;
    if(alreadyTriggered)
      return;

    [CATransaction begin];
    [CATransaction setCompletionBlock:
     ^{
       alreadyTriggered = YES;
     }];

    // Do me some animations...

    [CATransaction commit];
  };

  NSMutableDictionary* pageBlocks = [[NSMutableDictionary alloc] init];
  [pageBlocks setObject:[animationBlock copy] forKey:<animation name>];
  [self.animationBlocks setObject:pageBlocks forKey:<some page number>];

  [pageBlocks release];
  [animationBlock release];

"animation name" and "page number" are placeholders for explanation (these are arbitrary NSString literals).

And the code that runs these animations is as follows:

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
  int pageNumber = floor(self.scrollView.contentOffset.x / self.scrollView.frame.size.width);
  NSMutableDictionary* pageBLocks = [self.animationBlocks objectForKey:[NSString stringWithFormat:@"page%i",pageNumber]];
  [CATransaction begin];
  for(id key in pageBLocks)
    ((void (^)())[pageBLocks objectForKey:key])();
  [CATransaction commit];
 }

So far, so good, only if I pulled out the brochure from the navigation controller (like the dealloc calls in the brochure) and then reinsert it, the static bool is still installed.

My thoughts:

- ?   .. ( ) , dealloc .

- bool? bool , . Objective-C, . , popViewcOntroller. , ?

? Apple, , , . , ...?

+5
2

, , .

// ...
    BOOL shouldRemove = block();

    if (shouldRemove) {
        [pageBlocks removeObjectForKey:key];
    }
// ...


@interface TestClass : NSObject
@end

@implementation TestClass

- (void(^)(void))block;
{
    return [[^{

        static BOOL staticBOOL = NO;

        NSLog(@"%d", staticBOOL);

        staticBOOL = YES;

    } copy] autorelease];
}  

@end

int main(int argc, char *argv[]) {
    NSAutoreleasePool *p = [[NSAutoreleasePool alloc] init];

    TestClass *test1 = [[TestClass alloc] init];
    test1.block();
    test1.block();

    TestClass *test2 = [[TestClass alloc] init];
    test2.block();
    test2.block();

    [p release];
}


#=> 2012-04-23 00:43:38.501 Untitled[8380:707] 0
#=> 2012-04-23 00:43:38.503 Untitled[8380:707] 1
#=> 2012-04-23 00:43:38.503 Untitled[8380:707] 1
#=> 2012-04-23 00:43:38.504 Untitled[8380:707] 1

? , , ,

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView;
{
    NSInteger pageNumber = floor(self.scrollView.contentOffset.x / self.scrollView.frame.size.width);
    NSMutableDictionary *pageBlocks = [self.animationBlocks objectForKey:[NSString stringWithFormat:@"page%i", pageNumber]];

    [CATransaction begin];

    for (id key in [pageBlocks copy]) {
        void (^block)(void) = [pageBlocks objectForKey:key];
        if (block) {
            block();
        }
        [pageBlocks removeObjectForKey:key];
    }

    [CATransaction commit];
}
+1

, , ( dealloc ), bool .

, , - BOOL ... , , objc_setAssociatedObject().

UIViewController :

@interface UIViewController (OneShotAnimation)
@property ( nonatomic ) BOOL animationHasBeenPlayed ;
@end

@implementation UIViewController (OneShotAnimation)

-(void)setAnimationHasBeenPlayed:(BOOL)b
{
    objc_setAssociatedObject( self, @"animationHasBeenPlayed", [ NSNumber numberWithBool:b ], OBJC_ASSOCIATION_RETAIN_NONATOMIC ) ;
}

-(BOOL)animationHasBeenPlayed
{
    return [ objc_getAssociatedObject( self, @"animationHasBeenPlayed" ) boolValue ] ;
}

@end
0

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