【IOS笔记】分页功能

//
//  ViewController.m
//  分页功能1
//
//  Created by cdj on 17/9/10.
//  Copyright © 2017年 ue. All rights reserved.
//

#import "ViewController.h"

@interface ViewController () <UIScrollViewDelegate>
@property (strong, nonatomic) IBOutlet UIScrollView *scrollView;
@property (weak, nonatomic) IBOutlet UIPageControl *pageControl;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];



    //1.添加图片
    CGFloat scrollViewW = self.scrollView.frame.size.width;
    CGFloat scrollViewH = self.scrollView.frame.size.height;
    int count = 5;
    for (int i=0; i<count; i++) {
        UIImageView *imageView = [[UIImageView alloc] init];
        NSString *name = [NSString stringWithFormat:@"img_0%d", i+1];

        imageView.image = [UIImage imageNamed:name];
        imageView.frame = CGRectMake(i*scrollViewW, 0, scrollViewW, scrollViewH);
        [self.scrollView addSubview:imageView];
    }

//    2.设置contentSize
    self.scrollView.contentSize = CGSizeMake(count * scrollViewW, scrollViewH);


//    3分页
    self.scrollView.pagingEnabled = YES;

//    4.设置总页数
    self.pageControl.numberOfPages = count;

    self.pageControl.hidesForSinglePage = YES;
//    if (count <= 1) {
////        self.pageControl.alpha = 0;
//        self.pageControl.hidden = YES; //单页隐藏
//    }

//    5.
    [self.pageControl setValue:[UIImage imageNamed:@"current"] forKey:@"_currentPageImage"];
    [self.pageControl setValue:[UIImage imageNamed:@"other"] forKey:@"_pageImage"];



}
/**
 *  分页小圆点切换
 *
 *  @param scrollView <#scrollView description#>
 *  @param decelerate <#decelerate description#>
 */
//方式一
/*
-(void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{

    if (decelerate == NO) {

    }
}
-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{

    int page = scrollView.contentOffset.x / scrollView.frame.size.width;
    self.pageControl.currentPage = page;
}
*/

//方式二
-(void)scrollViewDidScroll:(UIScrollView *)scrollView{
//    四舍五入 int(小数部分＋0.5)

    int page = scrollView.contentOffset.x / scrollView.frame.size.width + 0.5;
    self.pageControl.currentPage = page;
}


@end

//
//  ViewController.m
//  分页功能1
//
//  Created by cdj on 17/9/10.
//  Copyright © 2017年 ue. All rights reserved.
//

#import "ViewController.h"

@interface ViewController () <UIScrollViewDelegate>
@property (strong, nonatomic) IBOutlet UIScrollView *scrollView;
@property (weak, nonatomic) IBOutlet UIPageControl *pageControl;

@property (nonatomic, weak) NSTimer *timer;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];



    //1.添加图片
    CGFloat scrollViewW = self.scrollView.frame.size.width;
    CGFloat scrollViewH = self.scrollView.frame.size.height;
    int count = 5;
    for (int i=0; i<count; i++) {
        UIImageView *imageView = [[UIImageView alloc] init];
        NSString *name = [NSString stringWithFormat:@"img_0%d", i+1];

        imageView.image = [UIImage imageNamed:name];
        imageView.frame = CGRectMake(i*scrollViewW, 0, scrollViewW, scrollViewH);
        [self.scrollView addSubview:imageView];
    }

//    2.设置contentSize
    self.scrollView.contentSize = CGSizeMake(count * scrollViewW, scrollViewH);


//    3分页
    self.scrollView.pagingEnabled = YES;

//    4.设置总页数
    self.pageControl.numberOfPages = count;

    self.pageControl.hidesForSinglePage = YES;
//    if (count <= 1) {
////        self.pageControl.alpha = 0;
//        self.pageControl.hidden = YES; //单页隐藏
//    }

//    5.
    [self.pageControl setValue:[UIImage imageNamed:@"current"] forKey:@"_currentPageImage"];
    [self.pageControl setValue:[UIImage imageNamed:@"other"] forKey:@"_pageImage"];

//    6.定时器，自动切换图片
    [self startTimer];



}
/**
 *  分页小圆点切换
 *
 *  @param scrollView <#scrollView description#>
 *  @param decelerate <#decelerate description#>
 */
//方式一
/*
-(void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{

    if (decelerate == NO) {

    }
}
-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{

    int page = scrollView.contentOffset.x / scrollView.frame.size.width;
    self.pageControl.currentPage = page;
}
*/

//方式二
-(void)scrollViewDidScroll:(UIScrollView *)scrollView{
//    四舍五入 int(小数部分＋0.5)

    int page = scrollView.contentOffset.x / scrollView.frame.size.width + 0.5;
    self.pageControl.currentPage = page;
}

-(void) nextPage:(NSTimer *)timer{
    NSLog(@"nextPage=%@", timer.userInfo);

    int page = self.pageControl.currentPage + 1;

    if (page >= 5) {
        page = 0;
    }

    [self.scrollView setContentOffset:CGPointMake(page * self.scrollView.frame.size.width, 0) animated:YES];
}

/**
 *  用户即将开启拖拽scrollView时，停止定时器
 *
 *  @param scrollView <#scrollView description#>
 */
-(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{

    [self stopTimer];
}
/**
 *  用户已经停止拖拽scrollView时，开启定时器
 *
 *  @param scrollView <#scrollView description#>
 *  @param decelerate <#decelerate description#>
 */
-(void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{
    [self startTimer];
}

-(void)startTimer{
    self.timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(nextPage:) userInfo:@"123" repeats:YES];
}
-(void)stopTimer{
    [self.timer invalidate];
    self.timer = nil;
}

@end