带下划线的注册按钮

先上效果图。

上代码：

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    //初始化按钮
    [self initRegisterButton];
}
#pragma -mark -funcitons
-(void)initRegisterButton
{
    //注册账号按钮
    UIButton *registerButton=[UIButton buttonWithType:UIButtonTypeRoundedRect];
    registerButton.frame=CGRectMake(50,100, 100, 20);
    registerButton.backgroundColor=[UIColor clearColor];
    [registerButton setTitle:@"注册账号" forState:UIControlStateNormal];
    [registerButton addTarget:self action:@selector(doClickRegisterButton:) forControlEvents:UIControlEventTouchUpInside];
    registerButton.titleLabel.textColor=[UIColor colorWithRed:144.0/255.0 green:144.0/255.0 blue:144.0/255.0 alpha:0.8];
    [self.view addSubview:registerButton];

    //注册账号下的线
    UIImageView *line=[[UIImageView alloc]initWithFrame:CGRectMake(registerButton.frame.origin.x+10, registerButton.frame.origin.y+registerButton.frame.size.height, 100, 1)];
    line.backgroundColor=[UIColor colorWithRed:144.0/255.0 green:144.0/255.0 blue:144.0/255.0 alpha:0.3];
    [self.view addSubview:line];

}
#pragma -mark -doClickButton
-(void)doClickRegisterButton:(UIButton *)btn
{
    NSLog(@"--doClickRegisterButton--");
}