Question

What is the best solution for simple iOS text/label animation? The details: user need to see one label on the iOS screen with changed text from array de 10-15 words, one word by step separated by white screen.The show time the one word is 800-900 ms and the show time the white screen is 500 ms. There is one kind of the attention test.

Answer 1

If you just want to flash words, you can use NSTimer or just performSelector:

@interface ViewController ()

@property (nonatomic, strong) NSArray *words;
@property (nonatomic) NSUInteger wordIndex;

@end

@implementation ViewController

static CGFloat const kWordShowInterval = 0.8;
static CGFloat const kWordHideInterval = 0.4;

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.words = @[@"one", @"two", @"three", @"four"];
    self.wordIndex = 0;

    [self showWord];
}

- (void)showWord
{
    if (self.wordIndex >= [self.words count])
        return;

    self.wordLabel.text = self.words[self.wordIndex];

    [self performSelector:@selector(hideWord)
               withObject:nil
               afterDelay:kWordShowInterval];
}

- (void)hideWord
{
    self.wordLabel.text = nil;

    self.wordIndex++;
    if (self.wordIndex < [self.words count])
    {
        [self performSelector:@selector(showWord)
                   withObject:nil
                   afterDelay:kWordHideInterval];
    }
    else
    {
        // all done, go ahead and invoke whatever you want to do when done presenting the words
    }
}

@end

If you wanted to do some animation of the appearance or disappearance of the text (e.g. fade it in or out), you could combine this with an animateWithDuration or other animation construct.