IOS 学习笔记,scrollView添加分页

#import "ViewController.h"
 
#define Width self.view.frame.size.width
#define Height self.view.frame.size.height
#define viewH 200
@interface ViewController ()<UIScrollViewDelegate>


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

@end

@implementation ViewController



#pragma mark - View lifecycle


- (void)viewDidLoad
{
 
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    self.scrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(0, Height-viewH, Width, viewH)];
    self.scrollView.delegate = self;
    [self.scrollView setContentSize:CGSizeMake(Width*4, viewH)];
    //self.scrollView.showsHorizontalScrollIndicator = YES;
    self.scrollView.showsVerticalScrollIndicator = YES;
    self.scrollView.pagingEnabled = YES;
    [self.scrollView setBackgroundColor:[UIColor redColor]];
    
    NSArray*arr =[[NSArray alloc]initWithObjects:[UIColor grayColor],[UIColor greenColor],[UIColor blueColor],[UIColor yellowColor], nil];
    for (int i=0; i<4; i++) {
        UIView * view1 = [[UIView alloc]initWithFrame:CGRectMake(Width*i, 0, Width, viewH)];
        [view1 setBackgroundColor:arr[i]];
        [self.scrollView addSubview:view1];

    }
    [self.view addSubview:self.scrollView];
    
    
    self.pageControl = [[UIPageControl alloc]initWithFrame:CGRectMake(0, 0, 200, 20)];
    self.pageControl.center = CGPointMake(Width/2, Height-20);
  
    self.pageControl.numberOfPages = 4;
    [self.pageControl addTarget:self action:@selector(pageChanged:) forControlEvents:UIControlEventValueChanged];
    
    [self.view addSubview:self.pageControl];
}
-(void)pageChanged:(UIPageControl*)page
{
    int p = (int)page.currentPage;
    [self.scrollView scrollRectToVisible:CGRectMake(Width*p, 0, Width, viewH) animated:YES];
}

-(void)scrollViewDidScroll:(UIScrollView*)scrollView
{
    CGFloat pageWith = scrollView.frame.size.width;
    int page = floor((scrollView.contentOffset.x - pageWith/2)/pageWith)+1;
    self.pageControl.currentPage = page;
}





- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end