obj-c concatenate int issue
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i'm new to obj-c and i'm trying to code a simple IBAction where a button once clicked change its label. it works good with image background and static string, but when it crashes on this:

    int i = (arc4random()%90);
    NSString *lab = [NSString stringWithFormat:@"%d", i];
    [sender setText:lab];

why? ty in advance