内外分离接口依赖及UIScrollView知识点

1:Class Extension 还能巧妙的解决一个接口暴露问题

有些属性或者方法对外可以提供，有些只针对内部的类进行调用；

// Sark.framework/Sark.h
@interface Sark : NSObject
@property (nonatomic, copy) NSString *name;
@property (nonatomic, copy) NSString *creditCardPassword; // secret!
@end

// Sark.framework/PrivateSarkWife.h
@interface PrivateSarkWife : NSObject
- (void)robAllMoneyFromCreditCardOfSark:(Sark *)sark; // needs password!
@end

假设 Sark.h 是 Sark.framework 唯一暴露的 Header，而 framework 中的一个私有类需要获取这个公共类的某个属性（或方法）该怎么办？PrivateSarkWife为Sark.framework内部一个类；上面的 creditCardPassword 属性需要一个对外不可见而对内可见的地方声明，这时候可以利用 Class Extension：

// Sark.h
@interface Sark : NSObject
@property (nonatomic, copy) NSString *name;
@end

// Sark+Internal.h <--- new
@interface Sark ()
@property (nonatomic, copy) NSString *creditCardPassword;
@end

// Sark.m
#import "Sark.h"
#import "Sark+Internal.h" // <--- new

将对公业务和对私业务用 Class Extension 的形式拆到两个 Header 中，在Sark.m里把两个头文件都进行引用，CreditCardPassword被定义在Sark+Internal.h的头文件里面，这样私有类对私有属性的依赖就被成功隔离开了：

// PrivateSarkWife.m
#import "PrivateSarkWife.h"
#import "Sark+Internal.h" // <--- 私有依赖

@implementation PrivateSarkWife
- (void)robAllMoneyFromCreditCardOfSark:(Sark *)sark {
    NSString *password = sark.creditCardPassword; // oh yeah!
}
@end

2:UIScrollView知识点

- (void)viewDidLoad
{
    [super viewDidLoad];

    scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(, , , )];
    scrollView.backgroundColor = [UIColor redColor];
    // 是否支持滑动最顶端
//    scrollView.scrollsToTop = NO;
    scrollView.delegate = self;
    // 设置内容大小
    scrollView.contentSize = CGSizeMake(, *);
    // 是否反弹
//    scrollView.bounces = NO;
    // 是否分页
//    scrollView.pagingEnabled = YES;
    // 是否滚动
//    scrollView.scrollEnabled = NO;
//    scrollView.showsHorizontalScrollIndicator = NO;
    // 设置indicator风格
//    scrollView.indicatorStyle = UIScrollViewIndicatorStyleWhite;
    // 设置内容的边缘和Indicators边缘
//    scrollView.contentInset = UIEdgeInsetsMake(0, 50, 50, 0);
//    scrollView.scrollIndicatorInsets = UIEdgeInsetsMake(0, 50, 0, 0);
    // 提示用户,Indicators flash
    [scrollView flashScrollIndicators];
    // 是否同时运动,lock
    scrollView.directionalLockEnabled = YES;
    [self.view addSubview:scrollView];

    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(, , , )];
    label.backgroundColor = [UIColor yellowColor];
    label.text = @"学习scrolleview";
    [scrollView addSubview:label];
    [label release];
}

#pragma mark -
/*
// 返回一个放大或者缩小的视图
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{

}
// 开始放大或者缩小
- (void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:
(UIView *)view
{

}

// 缩放结束时
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale
{

}

// 视图已经放大或缩小
- (void)scrollViewDidZoom:(UIScrollView *)scrollView
{
NSLog(@"scrollViewDidScrollToTop");
}
 */

// 是否支持滑动至顶部
- (BOOL)scrollViewShouldScrollToTop:(UIScrollView *)scrollView
{
    return YES;
}

// 滑动到顶部时调用该方法
- (void)scrollViewDidScrollToTop:(UIScrollView *)scrollView
{
    NSLog(@"scrollViewDidScrollToTop");
}

// scrollView 已经滑动
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    NSLog(@"scrollViewDidScroll");
}

// scrollView 开始拖动
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
    NSLog(@"scrollViewWillBeginDragging");
}

// scrollView 结束拖动
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
    NSLog(@"scrollViewDidEndDragging");
}

// scrollView 开始减速（以下两个方法注意与以上两个方法加以区别）
- (void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView
{
    NSLog(@"scrollViewWillBeginDecelerating");
}

// scrollview 减速停止
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
   NSLog(@"scrollViewDidEndDecelerating");
}

3:仿网易滚动菜单及内容视图滚动效果

#import "NewsViewController.h"

#import "VideoViewController.h"
#import "ReaderViewController.h"
#import "ScienceViewController.h"
#import "SocietyViewController.h"
#import "HotViewController.h"
#import "TopLineViewController.h"

#import "TitleButton.h"

#define ScreenW  [UIScreen mainScreen].bounds.size.width
#define ScreenH  [UIScreen mainScreen].bounds.size.height

@interface NewsViewController ()<UIScrollViewDelegate>

@property (nonatomic, strong) UIButton *selButton;

@property (nonatomic, strong) NSMutableArray *titleBtns;

// 标题滚动view
@property (weak, nonatomic) IBOutlet UIScrollView *titileScrollView;

// 内容滚动view
@property (weak, nonatomic) IBOutlet UIScrollView *contentView;

@end

@implementation NewsViewController

- (NSMutableArray *)titleBtns
{
    if (_titleBtns == nil) {
        _titleBtns = [NSMutableArray array];
    }
    return _titleBtns;
}

// 头条，热点，视频，社会，订阅，科技(science)

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    // 添加所有子控制器
    [self setUpChildViewController];

    // 设置标题
    [self setUpTitle];

    // iOS7之后,导航控制器下所有ScrollView都会添加额外滚动区域
    self.automaticallyAdjustsScrollViewInsets = NO;

    // 初始化scrollView
    [self setUpScrollView];

}

- (void)setUpScrollView
{
    self.titileScrollView.showsHorizontalScrollIndicator = NO;

    self.contentView.contentSize = CGSizeMake(self.childViewControllers.count * [UIScreen mainScreen].bounds.size.width, );

    self.contentView.showsHorizontalScrollIndicator = NO;
    self.contentView.pagingEnabled = YES;
    self.contentView.bounces = NO;

    self.contentView.delegate = self;
}

- (void)setUpChildViewController
{

    TopLineViewController *topLineVc = [[TopLineViewController alloc] init];
    topLineVc.title = @"头条";
    [self addChildViewController:topLineVc];

    HotViewController *hotVc = [[HotViewController alloc] init];
    hotVc.title = @"热点";
    [self addChildViewController:hotVc];

    VideoViewController *videoVc = [[VideoViewController alloc] init];
    videoVc.title = @"视频";
    [self addChildViewController:videoVc];

    SocietyViewController *societyVc = [[SocietyViewController alloc] init];
    societyVc.title = @"社会";
    [self addChildViewController:societyVc];

    ReaderViewController *readerVc = [[ReaderViewController alloc] init];
    readerVc.title = @"订阅";
    [self addChildViewController:readerVc];

    ScienceViewController *scienceVc = [[ScienceViewController alloc] init];
    scienceVc.title = @"科技";
    [self addChildViewController:scienceVc];
}

// 设置标题
- (void)setUpTitle
{
    NSUInteger count = self.childViewControllers.count;

    CGFloat btnX = ;
    CGFloat btnY = ;
    CGFloat btnW = ;
    CGFloat btnH = ;

    for (NSUInteger i = ; i < count; i++) {
        btnX = i * btnW;
        UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
        btn.tag = i;
        [btn setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
        UIViewController *vc = self.childViewControllers[i];
        [btn setTitle:vc.title  forState:UIControlStateNormal];
        [btn setTitleColor:[UIColor redColor] forState:UIControlStateSelected];
        btn.frame = CGRectMake(btnX, btnY, btnW, btnH);
        [btn addTarget:self action:@selector(titleClick:) forControlEvents:UIControlEventTouchUpInside];

        [self.titileScrollView addSubview:btn];

        [self.titleBtns addObject:btn];
        // 默认选中第一个
        if (i == ) {
            [self titleClick:btn];

        }
    }

    self.titileScrollView.contentSize = CGSizeMake(btnW * count, );

}

// 点击标题按钮
- (void)titleClick:(UIButton *)btn
{

    // 0.设置标题按钮居中
    [self setUpTitleBtnMiddle:btn];

    // 1.滚动到对应的界面
    CGFloat offsetX = btn.tag * ScreenW;

    self.contentView.contentOffset = CGPointMake(offsetX, );

    // 2.添加对应子控制器view到对应的位置
    UIViewController *vc = self.childViewControllers[btn.tag];

    vc.view.frame = CGRectMake(offsetX, , ScreenW, self.contentView.bounds.size.height);

//    NSLog(@"%@",NSStringFromCGRect(self.contentView.bounds));
    [self.contentView addSubview:vc.view];

    // 还原之前标题的形变
    [self setSelectBtn:btn];

}

- (void)setSelectBtn:(UIButton *)btn
{
    _selButton.transform = CGAffineTransformIdentity;
    [_selButton setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
    _selButton.selected = NO;

    btn.transform = CGAffineTransformMakeScale(1.3, 1.3);
    btn.selected = YES;

    _selButton = btn;

}

#pragma mark - UIScrollViewDelegate
// 减速完成的时候
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    // 获取当前的偏移量
    CGFloat offsetX = scrollView.contentOffset.x;
    // 获取页码
    int page = offsetX / scrollView.bounds.size.width;

    UIButton *btn = self.titileScrollView.subviews[page];

    // 选中按钮
    [self setSelectBtn:btn];

    // 设置按钮居中
    [self setUpTitleBtnMiddle:btn];

    // 添加对应子控制器到界面上
    UIViewController *vc = self.childViewControllers[page];

    // 已经加载的view就不需要添加了
    if (vc.isViewLoaded) return;

    vc.view.frame = CGRectMake(offsetX , , self.contentView.bounds.size.width, self.contentView.bounds.size.height);

    [self.contentView addSubview:vc.view];
}

// 设置标题按钮居中
- (void)setUpTitleBtnMiddle:(UIButton *)btn
{

    // 计算偏移量
    CGFloat offsetX = btn.center.x - ScreenW * 0.5;

    // 左边偏移多了，表示需要往左边看，可视范围往左边，偏移量就减少，最少应该是0
    if (offsetX < ) offsetX = ;
    CGFloat maxOffsetX = self.titileScrollView.contentSize.width - ScreenW;

    // 右边偏移多了，表示需要往右边看，可视范围往又边，偏移量就增加，最大不超过内容范围 - 屏幕宽度
    if (offsetX > maxOffsetX) offsetX = maxOffsetX;

    [self.titileScrollView setContentOffset:CGPointMake(offsetX, ) animated:YES];

}

// 监听内容view滚动
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    CGFloat page = scrollView.contentOffset.x / scrollView.bounds.size.width;

    NSInteger leftIndex = page;

    // 右边缩放比例
    CGFloat rightScale = (page - leftIndex);
    // 左边缩放比例
    CGFloat leftScale = ( - rightScale);

    NSInteger rightIndex = leftIndex + ;

    // 获取左边按钮
    TitleButton *leftBtn = self.titleBtns[leftIndex];

    NSInteger count = self.titleBtns.count;

    // 获取右边按钮
    TitleButton *rightBtn;

    if (rightIndex < count) {
       rightBtn  = self.titleBtns[rightIndex];
    }

    // 设置尺寸
    CGFloat leftTransform = leftScale * 0.3 + ; // 1 ~ 1.3
    CGFloat rightTransform = rightScale * 0.3 + ; // 1 ~ 1.3
    leftBtn.transform = CGAffineTransformMakeScale(leftTransform, leftTransform);
    rightBtn.transform = CGAffineTransformMakeScale(rightTransform, rightTransform);

    // 设置颜色
    /*
     RGB 红色: 1 0 0
         黑色: 0 0 0
     */

    UIColor *leftColor = [UIColor colorWithRed:leftScale green: blue: alpha:];
    UIColor *rightColor = [UIColor colorWithRed:rightScale green: blue: alpha:];

    [leftBtn setTitleColor:leftColor forState:UIControlStateNormal];
    [rightBtn setTitleColor:rightColor forState:UIControlStateNormal];

}

@end

效果图如下：