I want to pause the image from an array - ios

Question

I am creating an animation using the below code:
NSMutableArray *dashBoy = [NSMutableArray array];
for (int i = 1; i<= 20; i++) {
butterfly = [NSString stringWithFormat:#"5c_%d.jpg", i];
if ((image = [UIImage imageNamed:butterfly]))
[dashBoy addObject:image];
}
[stgImageView setAnimationImages:dashBoy];
[stgImageView setAnimationDuration:7.0f];
[stgImageView setAnimationRepeatCount:-1];
[stgImageView startAnimating];
My requirement is if dashBoy is 5c_10.jpg, then pause the image for about 5 sec and then resume animation and another if dashBoy is 5c_20.jpg, then pause the image again for about 5 sec and resume again. Is it possible?

Answer 1

You can't use variable speeds for UIImageView animations like this.
There are a couple of ways around it though.
1. Do it all yourself.
For this you would use something like an NSTimer and have it fire a method repeatedly to change the images for you. Using this you can time each image individually (you could even create a data object that holds an image and the length of time to show it and then create and array of these.
2. Manipulate the current method.
If you have 20 images and you want to show them all in 7 seconds then thats... 0.35 seconds per image. So a 5 second pause is about 14 images worth.
So instead of adding each image once you can add 1-9 once and then add 10 fourteen times. 11-19 once and then 20 fourteen times.
This will then swap like it is doing but when it reaches 10 it will swap it for another copy of the same image so it will look like it's pausing.
You will then have to increase the duration... to 17 seconds to get a similar duration for each image.
Which I'd do?
Although it sounds like a hack (because it is) I think I'd give the second method a go first. It's a lot easier to get working so if it does fail you haven't spent a long time setting it up.
The first method is a lot more work to set up but will allow for greater control of the animation.
Quick and dirty example for method 1
Create an object something like...
MyTimedImage
------------
UIImage *image
CGFloat duration
So for instance...
// probably want this as a property
NSMutableArray *timedImages = [NSMutableArray array];
MyTimedImage *timedImage = [MyTimedImage new];
timedImage.image = [UIImage imageNamed:[NSString stringWithFormat:#"5c_%d.jpg", i]];
timedImage.duration = 0.4;
[timedImages addObject:timedImage];
Then you want a way of displaying them...
//set up properties something like this...
#property (nonatomic, assign) NSInteger currentIndex;
#property (nonatomic, assign) BOOL paused;
#property (nonatomic, assign) NSTimer *imageTimer;
- (void)displayNextImage
{
if (self.paused) {
return;
}
NSInteger nextIndex = self.currentIndex + 1;
if (nextIndex == [self.timedImages count]) {
nextIndex = 0;
}
MyTimedImage *nextImage = self.timedImages[nextIndex];
self.currentIndex = nextIndex;
self.imageView.image = nextImage.image;
self.imageTimer = [NSTimer scheduledTimerWithInterval:nextImage.duration target:self selector:#selector(displayNextImage) userInfo:nil repeats:NO];
}
Using the properties that you've exposed you can pause the image view on the current image from a button press (for example).
To start the process just run [self displayNextImage]; you can start anywhere in the loop of images too.

Answer 2

using UIImageView animation, this is not possible, you may need to create your own animation logic like loading all UIImages in array and through timer, switch to next animation frame and when you desire to pause, invalidate the timer.