- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    // 1.创建按钮
    // 1.1.创建
    UIButton *btn = [[UIButton alloc] init];
    
    // 1.2.设置按钮的尺寸和位置
    btn.frame = CGRectMake(0, 0, 100, 100);
    
    // 1.3.设置按钮普通状态下的属性
    // 1.3.1.设置背景图片
    UIImage *normal = [UIImage imageNamed:@"btn_01.png"];
    [btn setBackgroundImage:normal forState:UIControlStateNormal];
    // 1.3.2.设置文字
    [btn setTitle:@"XX" forState:UIControlStateNormal];
    // 1.3.3.设置文字颜色
    [btn setTitleColor:[UIColor greenColor] forState:UIControlStateNormal];
    
    // 1.4.设置按钮高亮状态下的属性
    // 1.4.1.设置背景图片
    UIImage *high = [UIImage imageNamed:@"btn_02.png"];
    [btn setBackgroundImage:high forState:UIControlStateHighlighted];
    // 1.4.2.设置文字
    [btn setTitle:@"OO" forState:UIControlStateHighlighted];
    // 1.4.3.设置文字颜色
    [btn setTitleColor:[UIColor redColor] forState:UIControlStateHighlighted];
    
    // 1.5.监听按钮点击
    [btn addTarget:self action:@selector(btnClick:) forControlEvents:UIControlEventTouchUpInside];

    // 2.添加按钮到控制器的view中
    [self.view addSubview:btn];

}