iOS 界面启动时，功能新特征显示

APP新启动的时候，都会有几张新的图片滑动，才能到主的界面。现在，我们新建一个控制器，专门来处理新特性，直接上代码.

第一步：新建一个NewfeatureController

//
//  HWNewfeatureController.m
//  Weibo
//
//  Created by jys on 15/3/24.
//  Copyright (c) 2015年 weibo. All rights reserved.
//

#import "HWNewfeatureController.h"
#import "HWTabBarViewController.h"

#define HWNewfeatureCount 4

@interface HWNewfeatureController ()<UIScrollViewDelegate>

@property (nonatomic,weak) UIPageControl *pageControl;
@property (nonatomic,weak) UIScrollView *scrollView;

@end

@implementation HWNewfeatureController

- (void)viewDidLoad {
[super viewDidLoad];
//1.创建一个scrollView，显示所有的新特性图片
UIScrollView *scrollView=[[UIScrollView alloc] init];
scrollView.frame=self.view.bounds;
[self.view addSubview:scrollView];
self.scrollView=scrollView;

//2.添加图片到scrollView中
CGFloat scrollW=scrollView.width;
CGFloat scrollH=scrollView.height;

for (int i=0; i<HWNewfeatureCount; i++) {
UIImageView *imageView=[[UIImageView alloc] init];
imageView.width=scrollW;
imageView.height=scrollH;
imageView.y=0;
imageView.x=i*scrollW;

//显示图片
NSString *name = [NSString stringWithFormat:@"new_feature_%d", i + 1];
imageView.image=[UIImage imageNamed:name];
[scrollView addSubview:imageView];

// 如果是最后一个imageView，就往里面添加其他内容
if (i == HWNewfeatureCount - 1) {
[self setupLastImageView:imageView];
}
}

//3.设置scrollView的其它属性
//如果想要某个方向上不能滚动，那么这个方向对应的尺寸数值传0即可
scrollView.contentSize=CGSizeMake(scrollView.width*HWNewfeatureCount, 0);
scrollView.bounces=NO;//去除弹簧效应
scrollView.pagingEnabled=YES;//分页，一张一张的滚动
scrollView.showsHorizontalScrollIndicator=NO;//没有滚动条
scrollView.delegate = self;

//4.添加pageController分页，展示目前看的是第几页
UIPageControl *pageControl=[[UIPageControl alloc] init];
pageControl.numberOfPages=HWNewfeatureCount;
pageControl.backgroundColor=[UIColor redColor];
pageControl.currentPageIndicatorTintColor=HWColor(253, 98, 42);
pageControl.pageIndicatorTintColor=HWColor(189, 189, 189);
pageControl.centerX=scrollW*0.5;
pageControl.centerY=scrollH-50;
[self.view addSubview:pageControl];
self.pageControl=pageControl;

// UIPageControl就算没有设置尺寸，里面的内容还是照常显示的，该控件相对特别
//    pageControl.width = 100;
//    pageControl.height = 50;
//    pageControl.userInteractionEnabled = NO;
}

//当前页面滚到哪页
-(void)scrollViewDidScroll:(UIScrollView *)scrollView
{
double page=scrollView.contentOffset.x/scrollView.width;
self.pageControl.currentPage=(int)(page+0.5);
}

/**
*  初始化最后一个imageView
*
*  @param imageView <#imageView description#>
*/
-(void)setupLastImageView:(UIImageView *)imageView
{
//开启交互功能
imageView.userInteractionEnabled=YES;

//1.分享给大家
UIButton *shareBtn=[[UIButton alloc]init];
[shareBtn setImage:[UIImage imageNamed:@"new_feature_share_false"]  forState:UIControlStateNormal];
[shareBtn setImage:[UIImage imageNamed:@"new_feature_share_true"] forState:UIControlStateSelected];

[shareBtn setTitle:@"分享给大家" forState:UIControlStateNormal];
[shareBtn setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
shareBtn.titleLabel.font=[UIFont systemFontOfSize:15];
shareBtn.width=200;
shareBtn.height=30;
shareBtn.centerX=imageView.width*0.5;
shareBtn.centerY=imageView.height*0.65;
// top left bottom right
shareBtn.titleEdgeInsets = UIEdgeInsetsMake(0, 10, 0, 0);
[shareBtn addTarget:self action:@selector(shareClick:) forControlEvents:UIControlEventTouchUpInside];
[imageView addSubview:shareBtn];

//2.开始微博
UIButton *startBtn=[[UIButton alloc] init];
[startBtn setBackgroundImage:[UIImage imageNamed:@"new_feature_finish_button"] forState:UIControlStateNormal];
[startBtn setBackgroundImage:[UIImage imageNamed:@"new_feature_finish_button_highlighted"] forState:UIControlStateHighlighted];
startBtn.size=startBtn.currentBackgroundImage.size;
startBtn.centerX=imageView.width*0.5;
startBtn.centerY=imageView.height*0.75;
[startBtn setTitle:@"开始微博" forState:UIControlStateNormal];
[startBtn addTarget:self action:@selector(startClick) forControlEvents:UIControlEventTouchUpInside];
[imageView addSubview:startBtn];
//startBtn.centerX=imageView

}

-(void)shareClick:(UIButton *)shareBtn
{
//状态取反
shareBtn.selected=!shareBtn.isSelected;
}

//开始微博
-(void)startClick
{
UIWindow *window=[UIApplication sharedApplication].keyWindow;
window.rootViewController=[[HWTabBarViewController alloc]init];

}

@end

上面的代码中，需要注意的是：

开始微博，显示主界面时，请使用rootViewController来处理，如果用其它方式，新特性界面并没有销毁，留下隐患。

- (void)startClick
{
// 切换到HWTabBarController
/*
切换控制器的手段
1.push：依赖于UINavigationController，控制器的切换是可逆的，比如A切换到B，B又可以回到A
2.modal：控制器的切换是可逆的，比如A切换到B，B又可以回到A
3.切换window的rootViewController
*/
UIWindow *window = [UIApplication sharedApplication].keyWindow;
window.rootViewController = [[HWTabBarViewController alloc] init];

// modal方式，不建议采取：新特性控制器不会销毁
//    HWTabBarViewController *main = [[HWTabBarViewController alloc] init];
//    [self presentViewController:main animated:YES completion:nil];
}

第二步，程序启动时，判断版本号。如果版本号不一致，则显示新特性。

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
// 1.创建窗口
self.window = [[UIWindow alloc] init];
self.window.frame = [UIScreen mainScreen].bounds;

// 2.设置根控制器
NSString *key = @"CFBundleVersion";
// 上一次的使用版本（存储在沙盒中的版本号）
NSString *lastVersion = [[NSUserDefaults standardUserDefaults] objectForKey:key];
// 当前软件的版本号（从Info.plist中获得）
NSString *currentVersion = [NSBundle mainBundle].infoDictionary[key];

if ([currentVersion isEqualToString:lastVersion]) { // 版本号相同：这次打开和上次打开的是同一个版本
self.window.rootViewController = [[HWTabBarViewController alloc] init];
} else { // 这次打开的版本和上一次不一样，显示新特性
self.window.rootViewController = [[HWNewfeatureViewController alloc] init];

// 将当前的版本号存进沙盒
[[NSUserDefaults standardUserDefaults] setObject:currentVersion forKey:key];
[[NSUserDefaults standardUserDefaults] synchronize];
}

// 3.显示窗口
[self.window makeKeyAndVisible];
return YES;
}