How to send a time-delayed message to a UIView on a timer

Question

Hi,

I am adding UIViews to a superview in the following loop:

int xValue = 0 ;
int yValue = 10;
for (NSString *element in characters) {
    UIView *newCharView = [[MyChar alloc] initWithFrame:CGRectMake(xValue,yValue,100,100)];
    [(MyChar *)newCharView initLayers:element];
    [[self view] addSubview:newCharView];
    [newCharView autorelease];

    if (xValue <= 240) {
        xValue+=22;
    } else {
        xValue = 0;
        yValue += 22;
    }

}

MYChar contains a method which fires an animation. I want the method to be called sequentially in my loop with a delay of, say, 0.2 seconds. How can I achieve this? I tried delaying the animation itself but obviously just get the same delay in all the UIViews.

Answer 1

Give this a try:

[self performSelector:@selector(postAnimationMethod) withObject:self afterDelay:0.2];

Answer 2

You could try using something like this:

int xValue = 0 ;
int yValue = 10;
double delay = 0.2;
for (NSString *element in characters) {
    UIView *newCharView = [[MyChar alloc] initWithFrame:CGRectMake(xValue,yValue,100,100)];
    [self performSelector:@selector(delayedInitView:) withObject:element afterDelay:delay];

    if (xValue <= 240) {
        xValue+=22;
    } else {
        xValue = 0;
        yValue += 22;
    }
    delay += 0.2;

}

-(void) delayedInitView: (id) element {
    [(MyChar *) newCharView initLayers: element];
    [[self view] addSubview: newCharView];
    [newCharView autorelease];
}

You will have to experiment with that, as I don't know what exactly you are trying to achieve.

EDIT: Ouch, it's definitely not a good way to go with such a large amount of views. You could try using one background loop to init all of them. I would definitely have to think it over a lil more if I personally faced that problem, but here's a simple suggestion, you will have to tune it to your needs and probably take care of its thread/memory management safety:

[self performSelectorInBackground:@(backgroundInitViews:) withObject:characters]

-(void) backgroundInitViews: (NSArray*) elements {
    NSAutoreleasePool* pool = [[NSAutoreleasePool alloc] init];
    int xValue = 0 ;
    int yValue = 10;
    for (NSString *element in elements) {
        UIView *newCharView = [[MyChar alloc] initWithFrame:CGRectMake(xValue,yValue,100,100)];
        [(MyChar *) newCharView initLayers: element];
        [[self view] addSubview: newCharView];
        [newCharView autorelease];


        if (xValue <= 240) {
            xValue+=22;
        } else {
            xValue = 0;
            yValue += 22;
        }
        [NSThread sleepForTimeInterval:0.2];
    }
    [pool drain];
}