iOS Objective-c 左右滑动切换页面

ScrollView + n个view

1.storyboard布局一个ScrollView

2.拖出两个输出口，定义三个属性

@property (weak, nonatomic) IBOutlet UIScrollView *XMScrollView;
@property (weak, nonatomic) IBOutlet UIView *scrollContentView;


///第一次按下
@property (nonatomic) BOOL isBeginScroll;
///开始结束滑动scroll动画
@property (nonatomic) BOOL isBeginAnimationScroll;
///开始坐标
@property (nonatomic) NSInteger beginX;

3.在viewDidAppear中重新设置scrollContentView的布局宽和tableVIew大小和位置

///遍历布局
    for (NSLayoutConstraint *constraint in self.scrollContentView.constraints) {
       ///判断布局是不是自己想要的 NSLayoutAttribute类型
        if (constraint.firstAttribute == NSLayoutAttributeWidth) {
            
            [constraint setConstant:self.view.frame.size.width*3];
            
        }
     
    }

	[self.tableView1 setFrame:CGRectMake(0, 0, self.view.frame.size.width, scrollViewContentViewFrame.size.height)];
	        
	[self.tableView2 setFrame:CGRectMake(self.view.frame.size.width, 0, self.view.frame.size.width, scrollViewContentViewFrame.size.height)];
	        
	[self.tableView3 setFrame:CGRectMake(self.view.frame.size.width*2, 0, self.view.frame.size.width, scrollViewContentViewFrame.size.height)];

    
    

4.添加scrollView的代理方法

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{
    ///开始滑动scrollView
    self.isBeginScroll = YES;

    ///开始滑动scrollView的位置
    self.beginX = scrollView.contentOffset.x;;

}

- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset{
    ///停下自动滑动scrollView
    [self.XMScrollView setContentOffset:CGPointZero animated:YES];
    ///结束滑动scrollView
    self.isBeginScroll = NO;
    ///开始滑动动画
    self.isBeginAnimationScroll = YES;
    
}

///结束滑动动画
- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView{
    
    if (self.isBeginAnimationScroll) {
        
        CGFloat currentX = scrollView.contentOffset.x;
        
        NSInteger page = currentX/self.view.frame.size.width;
        ///判断到哪一页了,加载数据
        switch (page) {
                
            case 0:
                
  
                break;
                
            case 1:
                

                break;
                
            case 2:
                
    
                break;
                
            default:
                
                break;
                
        }
        
    }
    
    self.isBeginAnimationScroll = NO;

}

5.在viewDidLoad中添加监听

///页面切换ScrollView
    self.XMScrollView.delegate = self;
    
    [self addObserver:self forKeyPath:@"isBeginScroll" options:NSKeyValueObservingOptionNew context:nil];

6.通过监听实现滑动结束后自动滑动

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context{
    
    
    if (!self.isBeginScroll) {
        
        CGFloat offSetX = self.XMScrollView.contentOffset.x;
        
        NSInteger scale = (int)(offSetX/self.view.frame.size.width);
   
        if (offSetX >= self.beginX) {
  
                [self.XMScrollView setContentOffset:CGPointMake((scale+1)*self.view.frame.size.width, 0) animated:YES];
    
        }
        
        if (offSetX < self.beginX) {
            
            if (self.beginX >= self.view.frame.size.width){
       
                [self.XMScrollView setContentOffset:CGPointMake((scale)*self.view.frame.size.width, 0) animated:YES];

            }
            
        }
        
    }
    
}