重点！   

    对于启动页后的广告，相信大家也都看到过很多很多的，比如我自己常看到的有 QQ音乐，爱奇艺了。你点击了APP，它会启动就会随之启动。。其实这些APP的启动页是没有消失的，你去认真的观察一下！所以它们的顺序就变成了  点击 —> 启动页 —> 广告  下面是我截的QQ音乐的顺序图。不知道怎么弄GIF图。?

                               

 

      为什么说这是重点呢，可能有些小伙伴会误以为使用广告替代了启动页，但启动页怎样做成一个广告呢，还要加一些点击时间之类的，很是不懂！现在就清楚了，至少知道它的一个流程才会有思路的。

     还有一点，这个广告是缓存了的，你试着启动几次，它会给你不同的启动广告的，完事了，你把你的4G和Wifi都关掉，然后再去启动相应的APP，广告依旧是会出现的。。

一个思路：

     这里我说我的一个思路：

     1：把广告先封装到一个View当中去，然后把它加载到一个控制器当中显示，因为涉及到缓存和隐藏导航和标签栏的状况。

     2：在 APPDelegate 的   didFinishLaunchingWithOptions  中进行一个根视图的切换（同志们看了下面代码分析要觉得有问题，欢迎指正）。

这里是广告View的.m文件代码：

#import "AdvertisingView.h"#import "UIImageView+WebCache.h"@interface AdvertisingView()@property(nonatomic,strong) UIImageView * advertisingView;@property(nonatomic,strong) UIButton * advertisingJumpButton;@property(nonatomic,strong) UILabel * timeLabel;@property(nonatomic,assign) int secondsCountDown;@property(nonatomic,strong) NSTimer * countDownTimer;/** 定时器(这里不用带*，因为dispatch_source_t就是个类，内部已经包含了*) */@property (nonatomic, strong) dispatch_source_t timer;@end@implementation AdvertisingView/*// Only override drawRect: if you perform custom drawing.// An empty implementation adversely affects performance during animation.- (void)drawRect:(CGRect)rect {    // Drawing code}*/-(instancetype) initWithFrame:(CGRect)frame{    if (self = [super initWithFrame:frame]) {        [self addSubview:self.advertisingView];        [self addSubview:self.advertisingJumpButton];        [self addSubview:self.timeLabel];    }    return self;}-(void)startplayAdvertisingView:(void (^)(AdvertisingView *))advertisingview{    [[UIApplication sharedApplication].keyWindow addSubview:self];        [[UIApplication sharedApplication].keyWindow bringSubviewToFront:self];    // 这里的block advertisingview ;    // advertisingview(); 你要调用就要传参数过去，调用的具体代码在 APPdelegate 里面调用的时候添加这个 block具体的代码、、、    __block int count = 3;    // 获得队列    dispatch_queue_t queue = dispatch_get_main_queue();    // 创建一个定时器(dispatch_source_t本质还是个OC对象)    self.timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);    // 设置定时器的各种属性（几时开始任务，每隔多长时间执行一次）    // GCD的时间参数，一般是纳秒（1秒 == 10的9次方纳秒）    // 何时开始执行第一个任务    // dispatch_time(DISPATCH_TIME_NOW, 1.0 * NSEC_PER_SEC) 比当前时间晚3秒    dispatch_time_t start = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1.0 * NSEC_PER_SEC));    uint64_t interval = (uint64_t)(1.0 * NSEC_PER_SEC);    dispatch_source_set_timer(self.timer, start, interval, 0);    // 设置回调    dispatch_source_set_event_handler(self.timer, ^{        /**         *  回主线程更新UI         */        count--;        dispatch_async(dispatch_get_main_queue(), ^{                        if (count == 0) {                // 取消定时器                dispatch_cancel(self.timer);                self.timer = nil;                [self removeFromSuperview];                /**                 *  广告显示完，就调用 block 更换 rootcontroller                 */                advertisingview(self);               }            else{                _timeLabel.text = [NSString  stringWithFormat:@"%d",count];}        });    });    // 启动定时器    dispatch_resume(self.timer);}-(UIImageView * )advertisingView{    if (_advertisingView == nil) {           _advertisingView =[[UIImageView  alloc]initWithFrame:self.bounds];        [_advertisingView sd_setImageWithURL:[NSURL URLWithString:@"http://g.hiphotos.baidu.com/zhidao/pic/item/f2deb48f8c5494ee665ec00f29f5e0fe99257eac.jpg"] completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) {              }];    }      return _advertisingView;}-(UILabel * )timeLabel{     if (_timeLabel == nil) {                _timeLabel = [[UILabel alloc]initWithFrame:CGRectMake(self.bounds.size.width - 50, 50, 50, 40)];        _timeLabel.backgroundColor =[UIColor blackColor];        _timeLabel.alpha = 0.5;        _timeLabel.textColor = [UIColor whiteColor];      }      return _timeLabel;}-(UIButton * )advertisingJumpButton{    if (_advertisingJumpButton == nil) {               _advertisingJumpButton = [UIButton buttonWithType:UIButtonTypeCustom];        _advertisingJumpButton.frame =  CGRectMake(0, self.bounds.size.height - 80, self.bounds.size.width, 60);        [_advertisingJumpButton setTitle:@"了解详情" forState:UIControlStateNormal];        [_advertisingJumpButton setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];        [_advertisingJumpButton addTarget:self action:@selector(buttonclick) forControlEvents:UIControlEventTouchUpInside];        _advertisingJumpButton.titleLabel.font = [UIFont systemFontOfSize:18];        _advertisingJumpButton.backgroundColor = [UIColor blackColor];        _advertisingJumpButton.alpha = 0.5;        _advertisingJumpButton.contentHorizontalAlignment = UIControlContentHorizontalAlignmentRight;        _advertisingJumpButton.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;    }      return _advertisingJumpButton;}-(void)buttonclick{}@end

下面是添加这个View的控制器的.m文件：

#import "AdvertisingViewController.h"@interface AdvertisingViewController ()@end@implementation AdvertisingViewController/** *   可以在这个控制器里面做缓存？爱奇艺，QQ音乐的广告是缓存了的！ */-(void)viewWillAppear:(BOOL)animated{       [self setNeedsStatusBarAppearanceUpdate];}- (BOOL)prefersStatusBarHidden {      return YES;}-(void)viewDidLoad {      [super viewDidLoad];      [self.view addSubview:self.adverView];  }-(AdvertisingView *)adverView{      if (_adverView == nil) {              _adverView = [[ AdvertisingView alloc]initWithFrame:self.view.bounds];         }    return _adverView;}-(void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}/*#pragma mark - Navigation// In a storyboard-based application, you will often want to do a little preparation before navigation- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {    // Get the new view controller using [segue destinationViewController].    // Pass the selected object to the new view controller.}*/

 最重要的下面！！

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];    self.window.backgroundColor = [UIColor whiteColor];    /**     *  进来先让启动页沉睡 2 秒钟     */    [NSThread sleepForTimeInterval:2.0];     [[UIApplication sharedApplication] setStatusBarHidden:NO withAnimation:UIStatusBarAnimationFade];     AdvertisingViewController * adviewcontroller = [[AdvertisingViewController  alloc]init];    ZXTabBarController * tabbarcontroller = [[ZXTabBarController alloc]init];    // 这里要添加根控制器，不添加等下面添加是不行的。    self.window.rootViewController = adviewcontroller ;    [self.window makeKeyAndVisible];    [adviewcontroller.adverView startplayAdvertisingView:^(AdvertisingView * adverview) {       // 更换根控制器        self.window.rootViewController = tabbarcontroller;            }];    // Override point for customization after application launch.    return YES;} 

 总结一下：

       这样做，效果是实现了，但我心里一直的疑问就是在上面的更换根控制器这里，这样写效果是没问题的，下面我也会把效果图给大家看一下，本来这里我感觉就是这整个效果的一个核心的地方，大家要觉得有问题。。欢迎来撩！！要是你喜欢的话。。哈哈哈  

最后的效果图：