I was looking for a solution and DotSlashSlash has the answer hidden in one of the comments!
For the sake of completeness, the answer and the simplest solution is:
UIImage *myGradient = [UIImage imageNamed:@"textGradient.png"];
myLabel.textColor = [UIColor colorWithPatternImage:myGradient];
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…