iphone - getting UIImageView to repeatedly move - iphone

Question

Background: I am using xcode 3.1.4 and iphone simulator 3.1 (I know it's outdated and please dont comment about that).
Goal: I am trying to get a UIImageView that is created once the view loads to continuously move down. Creating the UIImageView works fine, but the move function does not work. Nothing happens. I use an NSTimer. Here is my code in the view controller.m file:
-(void)viewDidLoad{
UIImageView *six = [[UIImageView alloc]initWithImage:[UIImage imageNamed:#"Meteor.png"]];
CGRect rectSix = CGRectMake(arc4random() % (250), arc4random() % (1), 35, 35);
[six setFrame:rectSix];
[self.view addSubview:six];
[self moveMeteor:six];
[NSTimer scheduledTimerWithTimeInterval:0.2 target:self selector:#selector(moveMeteor:) userInfo:six repeats:YES];
}
-(void)moveMeteor:(UIImageView *)t{
t.center=CGPointMake(t.center.x, t.center.y + 1);
}
And of course, I declared my moveMeteor function in the view controller.h file. By typing in:
-(void)moveMeteor:(UIImageView *)t;
Any ideas of what the problem is and a solution to it?

Answer 1

Or you could do something like this, which takes advantage of UIView's animateWithDuration and should look much better. No timer required.
// in your interface declaration...
#property (nonatomic, assign) BOOL meteorShouldAnimate;
#property (weak, nonatomic) IBOutlet UIImageView *imageView;
// in your implementation...
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
self.meteorShouldAnimate = YES;
[self moveMeteorWithAnimationOptions:UIViewAnimationOptionCurveEaseIn]; // ease in to the animation initially
}
- (void)viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:animated];
self.meteorShouldAnimate = NO;
}
- (void)moveMeteorWithAnimationOptions: (UIViewAnimationOptions) options {
__weak MyViewController * weakSelf = self;
if (self.meteorShouldAnimate) {
[UIView animateWithDuration:0.2 delay:0.0 options:options animations:^{
self.imageView.transform = CGAffineTransformMakeTranslation(20.0, 20.0); // or whatever x and y values you choose
} completion:^(BOOL finished) {
MyViewController * strongSelf = weakSelf; // in case our view controller is destroyed before our completion handler is called
if (strongSelf) {
UIViewAnimationOptions nextOptions = strongSelf.meteorShouldAnimate ? UIViewAnimationOptionCurveLinear : UIViewAnimationOptionCurveEaseOut; // linear if we're continuing to animate, ease out if we're stopping
[strongSelf moveMeteorWithAnimationOptions:nextOptions];
}
}];
}
}

Answer 2

Your method is actually not getting the right parameter, you get NSTimer as a parameter. so instead
-(void)moveMeteor:(UIImageView *)t
the method should be like this
-(void)moveMeteor:(NSTimer *)timer
and you can't treat NSTimer as an UIImageView. :)
*Edit
I would suggest you to do something like
-(void)viewDidLoad{
UIImageView *six = [[UIImageView alloc]initWithImage:[UIImage imageNamed:#"Meteor.png"]];
CGRect rectSix = CGRectMake(arc4random() % (250), arc4random() % (250), 35, 35);
[six setFrame:rectSix];
[self.view addSubview:six];
[self moveMeteor:six];
[NSTimer scheduledTimerWithTimeInterval:0.2 target:self selector:#selector(moveMeteor:) userInfo:six repeats:YES];
}
and update your method to this
- (void)moveMeteor:(NSTimer *)timer {
UIImageView *six = timer.userInfo;
six.center=CGPointMake(six.center.x, six.center.y + 1);
}
just for information, I am passing the UIImageView in the dictionary as userInfo.