iPhone/iPad 启动视频的实现
原理

一些应用，在启动的时候加载了视频，感觉非常不错。实质上很简单：就是在 window的rootViewController上实现视频播放功能。下面的代码例子是实现播放在线视频功能，点击可退出。

代码
1. AppDelegate

// OpenVideoController.h#import <UIKit/UIKit.h>#import <MediaPlayer/MediaPlayer.h>@protocol OpenVideoControllerDelegate <NSObject>-(void)openVideoControllerDidStop;@end@interface OpenVideoController : MPMoviePlayerViewController@property(assign,atomic) BOOL isCallbacked;@property(assign)id<OpenVideoControllerDelegate> delegate;-(id)initWithDefault;@end// OpenVideoController.m#import "OpenVideoController.h"#import "SVProgressHUD.h"@interface OpenVideoController (PrivateOpenVideoController)-(void)popOpenVideo;@end@implementation OpenVideoController@synthesize delegate;@synthesize isCallbacked;-(id)initWithDefault{    NSURL *contentURL = [NSURL URLWithString: @"http://url-to-video/opening.mp4"];//online    //NSURL *contentURL = [[NSBundle mainBundle] URLForResource:@"opening" withExtension:@"mp4"];//local    self = [super initWithContentURL:contentURL];    if (self) {        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(playbackStateDidChange:) name:MPMoviePlayerPlaybackStateDidChangeNotification object:nil];        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(loadStateDidChange:) name:MPMoviePlayerLoadStateDidChangeNotification object:nil];        [[NSNotificationCenter defaultCenter] addObserver: self selector: @selector(playbackFinished:) name: MPMoviePlayerPlaybackDidFinishNotification object :nil];                isCallbacked = FALSE;    }    return self;}- (void)viewDidLoad{    [super viewDidLoad];        self.moviePlayer.scalingMode = MPMovieScalingModeAspectFill;    self.moviePlayer.controlStyle = MPMovieControlStyleNone;    [self.moviePlayer prepareToPlay];    [self.moviePlayer play];        UIView *tapView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 1024, 1024)];    tapView.backgroundColor = [UIColor clearColor];    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(viewTap:)];    [tapView addGestureRecognizer:tap];    [self.view addSubview:tapView];}- (void)viewDidAppear:(BOOL)animated{    [super viewDidAppear:animated];    [SVProgressHUD showWithStatus:@"视频缓冲中...点击跳过."];}-(void)viewTap:(id)sender{    //NSLog(@"-----viewTap: %d",self.moviePlayer.playbackState);    [self popOpenVideo];    }-(void)playbackStateDidChange:(NSNotification *)sender{    NSLog(@"-----playbackStateDidChange: %d",self.moviePlayer.playbackState);    if (self.moviePlayer.playbackState == MPMoviePlaybackStateStopped ) {        [self popOpenVideo];    }}- (void)playbackFinished:(NSNotification*)notification{            NSNumber* reason = [[notification userInfo] objectForKey:MPMoviePlayerPlaybackDidFinishReasonUserInfoKey];    switch ([reason intValue]) {        case MPMovieFinishReasonPlaybackEnded:            NSLog(@"-----Playback Ended");            break;        case MPMovieFinishReasonPlaybackError:            NSLog(@"-----Playback Error");            break;        case MPMovieFinishReasonUserExited:            NSLog(@"-----User Exited");            break;        default:            break;    }    NSLog(@"-----playbackFinished: %d",[reason intValue]);            [self popOpenVideo];}-(void)loadStateDidChange:(NSNotification *)sender{    //NSLog(@"-----loadStateDidChange: %d",self.moviePlayer.loadState);    if(self.moviePlayer.loadState == MPMovieLoadStatePlayable){        [SVProgressHUD dismiss];    }}- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation{    return UIInterfaceOrientationIsLandscape(interfaceOrientation);    //return YES;}-(void)dealloc{    [[NSNotificationCenter defaultCenter] removeObserver:self name:MPMoviePlayerPlaybackStateDidChangeNotification object:nil];    [[NSNotificationCenter defaultCenter] removeObserver:self name:MPMoviePlayerLoadStateDidChangeNotification object:nil];    [[NSNotificationCenter defaultCenter] removeObserver:self name:MPMoviePlayerPlaybackDidFinishNotification object:nil];    [SVProgressHUD dismiss];    //NSLog(@"--------open video controller delloc");}-(void)popOpenVideo{    @synchronized(self){        if (!isCallbacked) {            if (delegate && [delegate respondsToSelector:@selector(openVideoControllerDidStop)]) {                isCallbacked = TRUE;                [delegate openVideoControllerDidStop];            }        }    }}@end

4. MainViewController

MainViewController 就是普通的 ViewController 了，主要是替换 window 的 rootController

说明：

1. 由于加载的是在线视频，所以，使用了类库：SVProgressHUD

2. 基于上面原因，若是本地视频的话，则可去了 SVProgressHUD 相关的代码。

3. 总体来说，代码还是相当简单的。

THE END.