块动画 - 如何循环 UIImage 数组

Question

I'm going the direction of block animations, having tried to implement multiple animations and an "on finish" event with UIImageView animations but failing.

I have a UIImage array, which I need to cycle backwards through, displaying as I go. Here is what I have so far:

__block int i = 9;
[UIView animateWithDuration:4.0
                 animations:^{
                     self.fooView.image = fooImage[i];
                     [self.view addSubview:self.fooView];
                     i--;
                }
                 completion:NULL];

This does happily display the 9th element of fooImage[], but it doesn't iterate through the rest.

Is this a misunderstanding about what blocks can actually do in this context? I tried to also wrap a while loop, decrementing "i", but I ended up with the first element only (I sort of expected that). How should one iterate through an array in this instance - perhaps have 9 different animation blocks?

Any tips will be gratefully received, and thanks for your time

sc.

Answer 1

Your animations completion handler is NULL, which means nothing is happened after animation is completed. And it's strange to use animations block if you actually animate nothing. Animations won't wait 4 seconds before calling competition handler if there is nothing to animate.

__block int i = 9;
void(^process)(void(^recursive)());
process = ^(void(^recursive)()) {
    --i;
    [UIView animateWithDuration:4.0
                     animations:^{
                         NSLog(@"%d", i);
                     }
                     completion:^(BOOL finished) {
                         recursive(recursive);
                     }];
};
process(process);