This is a subclass of UILabel to draw outline characters.
UIOutlineLabel *label = [[UIOutlineLabel alloc] init];
// configuration of UILabel
label.frame = CGRectMake(0, 0, 100, 50);
label.textColor = [UIColor whiteColor];
label.font = [UIFont boldSystemFontOfSize:30];
label.text = @"Hello world";
// configuration of UIOutlineLabel
label.outlineColor = [UIColor blackColor]; // color of outline
label.outlineSize = 3; // size of outline
[self.view addSubview:label];