UIButton分两段设置渐变色

_loginBtn=[[UIButton alloc]initWithFrame:CGRectMake(40*PIX, 100*PIX, ScreenWidth-80*PIX, 88*PIX)];
    [_loginBtn setTitle:@"下一步" forState:UIControlStateNormal];
    //渐变颜色
    CAGradientLayer*_gradientLayer = [CAGradientLayer layer];
    _gradientLayer.colors = @[(__bridge id)rgb(40,129,252).CGColor, (__bridge id)rgb(31,76,225).CGColor];
    _gradientLayer.startPoint = CGPointMake(0, 0);
    _gradientLayer.endPoint = CGPointMake(1.0, 0);
    _gradientLayer.frame = _loginBtn.bounds;
    _gradientLayer.cornerRadius = 44*PIX;
    [_loginBtn.layer addSublayer:_gradientLayer];
    [footerView addSubview:_loginBtn];
    _loginBtn.titleLabel.font=[UIFont systemFontOfSize:K_30Size];
    [_loginBtn addTarget:self action:@selector(nextBtnDidClicked) forControlEvents:(UIControlEventTouchUpInside)];