iOS开发——如何做一个漂亮的引导页

- (void)setGuidePageImageFrame{    for (int i = 0; i < 4; i++) {        UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake([[UIScreen mainScreen] bounds].size.width * i, 0, [[UIScreen mainScreen] bounds].size.width, [[UIScreen mainScreen] bounds].size.height)];        [imageView setUserInteractionEnabled:true];        [imageView setImage:[UIImage imageNamed:[NSString stringWithFormat:@"guidepage%d",i]]];        [self.guidepageScrollView addSubview:imageView ];          }      UIView *view = [[UIView alloc] initWithFrame:CGRectMake([[UIScreen mainScreen] bounds].size.width * 4, 0, [[UIScreen mainScreen] bounds].size.width, [[UIScreen mainScreen] bounds].size.height)];  [view setUserInteractionEnabled:true];  [view setBackgroundColor:[UIColor colorWithPatternImage:[UIImage imageNamed:@"guidepage0.png"]]];      UIButton *loginButton = [[UIButton alloc] initWithFrame:CGRectMake((UISCREEN_WIDTH - 200) / 3, UISCREEN_HEIGHT - 100, 100, 30)];  [loginButton setTitle:@"登录" forState:UIControlStateNormal];  [loginButton.layer setBorderColor:[UIColor whiteColor].CGColor];  [loginButton.layer setBorderWidth:0.5];  [loginButton.layer setMasksToBounds:true];  [loginButton addTarget:self action:@selector(loginButtonPressed:) forControlEvents:UIControlEventTouchUpInside];    UIButton *registerButton = [[UIButton alloc] initWithFrame:CGRectMake((UISCREEN_WIDTH - 200) / 3 + (UISCREEN_WIDTH - 200) / 3 + 100, UISCREEN_HEIGHT - 100, 100, 30)];  [registerButton setTitle:@"注册" forState:UIControlStateNormal];  [registerButton.layer setBorderColor:[UIColor whiteColor].CGColor];  [registerButton.layer setBorderWidth:0.5];  [registerButton.layer setMasksToBounds:true];  [registerButton addTarget:self action:@selector(registerButtonPressed:) forControlEvents:UIControlEventTouchUpInside];    [view addSubview:loginButton];  [view addSubview:registerButton];    [self.guidepageScrollView addSubview:view];    }

（4）大家仔细观看引导页可以看到，下面还有一个指示当前页面的控件，叫做PageControl，可以显示出共有几页并且当前在哪一页。这部分我用代码来实现。

1）.定义一个PageControl：

@property(nonatomic,strong)UIPageControl *pageControl;

2) .在viewDidLoad中初始化PageControl的属性：

- (void)viewDidLoad {  [super viewDidLoad];    self.pageControl  = [[UIPageControl alloc] initWithFrame:CGRectMake([[UIScreen mainScreen] bounds].size.width / 2 - 50, [[UIScreen mainScreen] bounds].size.height - 50, 100, 20)];  self.pageControl.numberOfPages = 5;  [self.view addSubview:self.pageControl];    [self setGuidePageScrollViewFrame];}

3).实现ScrollView的delegate（UIScrollViewDelegate）,根据ScrollView的滚动偏移位置来判断当前在哪个页面，也就是计算ScrollView的水平滚动，代码如下：

- (void)scrollViewDidScroll:(UIScrollView *)scrollView{    CGFloat offsetWidth = self.guidepageScrollView.contentOffset.x;  int pageNum = offsetWidth / [[UIScreen mainScreen] bounds].size.width;  self.pageControl.currentPage = pageNum;      }

（5）经过以上步骤，基本的引导页功能就实现了。但是还有非常重要的一个业务逻辑：引导页只有在第一次安装的时候出现，以后启动App就不会出现了。这里就可以使用NSUserDefaults来记录。启动App我们就可以判断该值是否为空，为空表示是第一次安装，显示引导页，否则就直接跳到其他界面。

代码如下：可以这样简单的存储进行判断。