Question

I’m trying to create a typewriter effect.
my code works fine. My problem, and this … UITextView fails to update in real time. this is my code:

NSMutableArray *testochar=[util getTestoChar:value];

for (int i=0; i<[testochar count]; i++){
    NSString *y=[testochar objectAtIndex:i];

    [NSThread sleepForTimeInterval:0.1f];

    self.txtview.text=[self.txtview.text stringByAppendingString:y];
}

Answer 1

All modification on UI you should do in main thread, try use performSelectorOnMainThread:withObject:waitUntilDone:

call

    //...
    for(int i=0;i<[testochar count];i++){
        NSString *y=[testochar objectAtIndex:i];
        [NSThread sleepForTimeInterval:0.1f];
        NSDictionary *arg =  [NSDictionary dictionaryWithObjectAndKeys:
                self.txtview, @"textView",
                y, @"string", nil ];
       [self performSelectorOnMainThread:@selector(updateTextForTextView:) withObject:arg waitUntilDone:NO];
    }

//.....


-(void)updateTextForTextView:(NSDictionary*)arg {
    NSString *string = [arg objectForKey:@"string"];
    UITextView *textView = [arg objectForKey:@"textView"];
    self.txtview.text=[self.txtview.text stringByAppendingString:string];
}

(update)

try

- (void)viewDidLoad {
    [super viewDidLoad];

    textView.text = @"";


    [[NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(update) userInfo:nil repeats:YES] retain];
}


-(void) update {
    static char text[] = "HELLO";
    static int i =0;

    if (text[i%6]==0) {
        textView.text = [NSString stringWithFormat:@""];
    } else {
        textView.text = [NSString stringWithFormat:@"%@%c", textView.text, text[i%6] ];
    }
    i++;
}

it works like:
http://www.youtube.com/watch?v=tB2YKX4zpY4