How to click the button to modify the text size

I am currently developing an iphone application. I need to click a button to modify the text size in the tag. I don't know how to implement this function? It should be developed in ios5. Thank you for your advice ~~ Solution: Create UILabel [plain] self. lbl = [[UILabel alloc] initWithFrame: CGRectMake (135,290,200, 35)]; self. lbl. backgroundColor = [UIColor clearColor]; NSString * str = [NSString stringWithFormat: @ "%. f ", [self. slider value]; [self. lbl setFont: [UIFont fontWithName: @ "Arial-BoldMT" size: 16]; self. lbl. text = str; www.2cto.com [self. view addSubview: self. lbl]; when you click UIButton, modify the UILabel text size [plain]-(IBAction) ButtonPressed :( id) sender {[self. lbl setFont: [UIFont fontWithName: @ "Arial-BoldMT" size: 25];}