How to achieve that effect ?

[iph_s]

I have an array that contains numbers from 1 to 200.
What I want is these numbers to be randomly displayed in UILabel for let's say 5 seconds and at the end only one number to be displayed (let's say the winner number).
How to do that ?

[itsaboutcode]

Originally Posted by iph_s

I have an array that contains numbers from 1 to 200.
What I want is these numbers to be randomly displayed in UILabel for let's say 5 seconds and at the end only one number to be displayed (let's say the winner number).
How to do that ?

You have to create a loop which will run five times. Once you have found the random number, display it in UILabel and after that wait for 5 sec.

To Find the random number: Random number in iphone sdk? - Stack Overflow

To wait for n sec, check this: Sleep, Pause or Block a Thread

[iph_s]

This is not what I looking for. I know how to make random generator etc, but I don't know how to animate the process. I want to know how to animate the numbers in UILabel.

[itsaboutcode]

Originally Posted by iph_s

This is not what I looking for. I know how to make random generator etc, but I don't know how to animate the process. I want to know how to animate the numbers in UILabel.

Checkout following links - I hope they will help you out.

How to use iPhone Timers and Animated Views

ipad - setting new text to uilabel and animation - Stack Overflow

ipad - iPhone UILabel animation - Stack Overflow

[Duncan C]

Originally Posted by iph_s

This is not what I looking for. I know how to make random generator etc, but I don't know how to animate the process. I want to know how to animate the numbers in UILabel.

Record the current time to an NSTimeInterval instance variable:

NSTimeInterval startTime;

startTime = [NSDate timeintervalSinceReferenceDate];

Start an NSTimer that fires say, 4 times a second. Have that timer call a method, changeLabel:. Make your changeLabel method follow the signature for timer methods (it needs to have 1 parameter: the timer itself.)

In your changeLabel method, pick a random number, use it as an index into your array, and install the value at that index into your label.

Check to see if your time period (5 seconds) has elapsed. If it has, kill your timer.

if ([NSDate timeintervalSinceReferenceDate] - startTime >= 5)
   [theTimer invalidate];

Are you asking how to do some sort of animation for updating your label? If so, what kind of animation?

[iph_s]

Here is what I want to achieve. Please see the animated gif.

[Duncan C]

Originally Posted by iph_s

Here is what I want to achieve. Please see the animated gif.

See my post then. I told you exactly what to do.

[RickSDK]

you'll need to do the animations in a background thread

put this lin in viewDidLoad:

[self performSelectorInBackground:@selector(foo) withObject:nil];


then add this function:

-(void)foo
{
NSAutoreleasePool *aPool = [NSAutoreleasePool alloc] init];

// do the work

[aPool drain];
}

[Speed]

Originally Posted by RickSDK

you'll need to do the animations in a background thread

put this lin in viewDidLoad:

[self performSelectorInBackground:@selector(foo) withObject:nil];


then add this function:

-(void)foo
{
NSAutoreleasePool *aPool = [NSAutoreleasePool alloc] init];

// do the work

[aPool drain];
}

If it is intensive work, he should do the work in a background thread and update the user interface on the main thread.

[iph_s]

@Duncan C,
Thans a lot !

[Duncan C]

Originally Posted by RickSDK

you'll need to do the animations in a background thread

put this lin in viewDidLoad:

[self performSelectorInBackground:@selector(foo) withObject:nil];


then add this function:

-(void)foo
{
NSAutoreleasePool *aPool = [NSAutoreleasePool alloc] init];

// do the work

[aPool drain];
}

This is absolutely and completely wrong. Do not follow this advice.

What the OP asked for was a simple cycle of values. It is not appropriate for a background thread for 2 reasons:

• Picking a random item and updating a label take almost no time.
• All changes to the UI need to be done on the main thread. Altering UI Elements in the background causes unexpected results, and even crashes.