Trying to perform multiple animations at once - ios

Question

Seems strange that i could not find any answer for this all over the net, but seems that if you want to move 6 UIViews at the same time in a different speed ,you can't do that.
If i am using one of this 2 example, i get that sometimes only some of the views are moving, and sometimes all of them (as expected) .
There is no way to move 6-7-8 UIViews at the same time ,with different duration?
1.
for(UIButton *button in buttons)
{
float r= arc4random()%10;
float t =0.1+ 1.0/r;
[UIView beginAnimations:#"Anim0" context:nil];
[UIView setAnimationDuration:t];
[UIView setAnimationCurve:UIViewAnimationCurveEaseIn];
[UIView setAnimationTransition:UIViewAnimationTransitionNone forView:button cache:YES];
CGRect newframe=button.frame;
newframe.origin.y=0;
button.frame=newframe;
[UIView commitAnimations];
}
2.
for(UIButton *button in buttons)
{
int random=arc4random()%10;
float time=0.5+ 1/(float)random;
CGRect newframe=button.frame;
newframe.origin.y=0;
[UIView transitionWithView:button
duration:time
options:UIViewAnimationOptionCurveEaseInOut
animations:^{
button.frame=newframe;
}
completion:nil];
}

Answer 1

You need to limit the random number generator.
Your function...
arc4random() % 10;
Will sometimes return 0.
Then passing this into...
float time = 0.5 + 1/random;
Will make time = inf.
You can see this by logging out the time values.
A time of inf will make the button not animate.

Answer 2

Of course it is possible. The problem is that you're sending the wrong message. Based on your second snippet, this is an example of how it could be done:
for (UIButton *button in self.buttons) {
int random = (arc4random() % 10) + 1; // "+1" Added later in the answer, see Fogmeister's answer
float time = 0.5 + 1 / (float)random;
CGRect newframe = button.frame;
newframe.origin.y = 0;
[UIView animateWithDuration:time
delay:0.0f
options:UIViewAnimationOptionCurveEaseInOut
animations:^{
button.frame = newframe;
} completion:^(BOOL finished) {
// The animation have finished
}];
}