Question

I try to refresh background image of an uibutton, this is the code for create button

- (void) disegnaAnteprime {

int x = 2;
int y = 2;
int i = 0;

scrollView.contentSize = CGSizeMake(self.view.frame.size.width, 10*103);

for (i=0; i < arrayProgetti.count;i++) {

    NSNumber *indice = [NSNumber numberWithInt:i];

    elemento = [arrayProgetti objectAtIndex:i];

    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    [button setTitle:[elemento objectForKey:@"Titolo"] forState:UIControlStateNormal];

    [button addTarget:self action:@selector(openPdf:) forControlEvents:UIControlEventTouchUpInside];
    [button setContentVerticalAlignment:UIControlContentVerticalAlignmentBottom];
    button.tag = i;

    NSURL *indirizzoImmagine = [NSURL URLWithString:[elemento objectForKey:@"IndirizzoIcona"]];

    NSLog(@"Indice i: %d",i);

    NSData *imageData = [cache cachedResponseDataForURL:indirizzoImmagine]; 

    if (imageData==nil) {
        [self loadURL:indirizzoImmagine idElementoBottone:indice tipoRichiesta:NO];
    }
    else {
        [button setImage:[UIImage imageWithData:imageData] forState:UIControlStateNormal];        
    }

    button.frame = CGRectMake(30, y, 190, 190);
    y = y + 192;

    [self.scrollView addSubview:button];
}

}

while this is the code that I use for refresh button image

- (void)requestFinished:(ASIHTTPRequest *)request
{
      int tag = [[request.userInfo objectForKey:@"TagBottone"] intValue];        
      NSLog(@"Tag: %d",tag);

      [(UIButton*)[self.scrollView viewWithTag:tag] setTitle:@"hello" forState:UIControlStateNormal];        

}

but I get this error

[UIScrollView setTitle:forState:]: unrecognized selector sent to instance 0x8179eb0
2012-03-28 23:54:40.477 iVision[2269:15b03] * Terminating app due to uncaught exception ‘NSInvalidArgumentException’, reason: ‘-[UIScrollView setTitle:forState:]: unrecognized selector sent to instance 0x8179eb0’
* First throw call stack:
(0x1c5f052 0x37f3d0a 0x1c60ced 0x1bc5f00 0x1bc5ce2 0xd574 0x1c60e72 0x37d0b 0x1c60e72 0x12879ef 0x1c3397f 0x1b96b73 0x1b96454 0x1b95db4 0x1b95ccb 0x1df1879 0x1df193e 0x96fa9b 0x3560 0x2d85)

where is the mistake?
edit:for now I try only to change titletex.

thank you!

Answer 1

This states that you are trying to use setTitle:forState: in a scrollView rather than a UIButton. Have you tried separating the code:

UIButton * btn = (UIButton*)[self.scrollView viewWithTag:tag];
[btn setTitle:@"hello" forState:UIControlStateNormal];

You can also check if your casting is succeeding:

if([[self.scrollView viewWithTag:tag] isKindOfClass:[UIButton class]])
{
    UIButton * btn = (UIButton*)[self.scrollView viewWithTag:tag];
    [btn setTitle:@"hello" forState:UIControlStateNormal];
}

It all indicates that the result of viewWithTag is not a UIButton. UIScrollView has some subviews itself. I would start your tags with a value of 100 and then, just add 100 to the result of the request. This avoids conflicts with existing subviews.

Hope it helps.