存储用户的偏好设置,存储在本地, 比如程序是否是第一次加载
NSUserDefaults * userDefults = [NSUserDefaults standardUserDefaults];

if (![userDefults boolForKey:@"aa"]) {

[self setupFirstLanchView];

[userDefults setBool:YES forKey:@"aa"];

[userDefults synchronize]; 立即同步. .

}


创建程序第一次加载要显示的视图
- (void)setupFirstLanchView
{
[self setupScrollView];
[self setupPageControl];
}