UIImage * CharacterBtnImage = [UIImage imageNamed:@"whiteBack"];
CharacterBtnImage = [CharacterBtnImage stretchableImageWithLeftCapWidth:CharacterBtnImage.size.width * 0.5 topCapHeight:CharacterBtnImage.size.height * 0.5];
UIButton * btn1 = [UIButton buttonWithType:UIButtonTypeCustom];
btn1.frame = CGRectMake(10, 100, 280, 50);
[btn1 setTitle:@"登陆" forState:UIControlStateNormal];
[btn1 setTitleColor:[UIColor redColor] forState:UIControlStateNormal];
[self.view addSubview:btn1];
// 这里一定要用 setBackgroundImage
[btn1 setBackgroundImage:CharacterBtnImage forState:UIControlStateNormal];
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