iphone textview update while cycle running thread - iphone

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

Answer 2

really thanks for your advice. I did it by modifying the code this way.
1) self.timer = [[NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:#selector(update) userInfo:nil repeats:YES] retain];
-(void) update {
char text[[self.testo length]];
for(int i=0;i<self.testo.length;i++){
text[i]=[self.testo characterAtIndex:i];
}
static int i =0;
if (i==self.testo.length) {
/// txtview.text = [NSString stringWithFormat:#""];
[self.timer invalidate];
} else {
txtview.text = [NSString stringWithFormat:#"%#%c", txtview.text, text[i%self.testo.length] ];
}
i++;
}