btn1=[UIButton buttonWithType:UIButtonTypeRoundedRect];
    [btn1 setTitle:@"OK" forState:UIControlStateNormal];
    [btn1 setFrame:CGRectMake(10, 10, 100, 50)];
    [self.view addSubview:btn1];
    [btn1 release];这是源码,为什么运行后,Button的title没法显示呢?