If you have an IBOutlet Object.
theButton.transform = CGAffineTransformMakeRotation(M_PI / -4);
If you want to create run time button on view.
- (void)viewDidLoad {
[super viewDidLoad];
UIButton *btn=[UIButton buttonWithType:UIButtonTypeRoundedRect];
[btn setFrame:CGRectMake(100, 100, 200, 44)];
btn.transform=CGAffineTransformMakeRotation(M_PI / -4);
[btn setTitle:@"RakeshBhatt" forState:UIControlStateNormal];
[self.view addSubview:btn];
}