效果图
UIScrollView - 图片轮播.gif
#import "ViewController.h"
@interface ViewController ()<UIScrollViewDelegate>
@property (weak, nonatomic) IBOutlet UIScrollView *scrollView;
@property (weak, nonatomic) IBOutlet UIPageControl *pageControl;//分页指示器
@property (assign, nonatomic) int pageNo; //分页码 scrollOffset
@property(nonatomic) int pageSum;// 总页数
@property (assign, nonatomic) CGFloat scrollMaxX; //scrollView最大x轴宽度
@property (assign, nonatomic) CGFloat scrollVisibleW;//scrollView可视区宽度
@property (assign, nonatomic) CGPoint scrollOffset;//scrollView的偏移量
@property (strong, nonatomic) NSTimer * timerImgScroll;//图片轮播定时器
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
UIImage *imageTemp;
UIImageView *imgViewText;
self.pageSum = 5;// 总页数
CGFloat imgViewY = 0;
CGFloat imgViewW = 375;
CGFloat imgViewH = 260;
for (int i=0; i<5; i++) {
NSString *imgName = [NSString stringWithFormat:@"img_%02d",i+1];
imageTemp = [UIImage imageNamed:imgName];
imgViewText = [[UIImageView alloc]initWithImage:imageTemp];
imgViewText.frame = CGRectMake(i*imgViewW, imgViewY, imgViewW, imgViewH);
[self.scrollView addSubview:imgViewText];
}
//CGFloat imgViewMaxX = CGRectGetMaxX(imgViewText.frame);
self.scrollMaxX = CGRectGetMaxX(imgViewText.frame);
//告诉scrollView内容有多大
self.scrollView.contentSize = CGSizeMake(self.scrollMaxX, 0);
//不显示水平方向的滚动条
self.scrollView.showsHorizontalScrollIndicator = NO;
/*
启用分页控件
scrollView是以多少宽度,进行分页得?
答:以scrollView自身的宽度为一页,进行分页得!
*/
self.scrollView.pagingEnabled = YES;
/*
PageControl
Tint Color (其它颜色) Current Color(现在颜色)
numberOfPages (总共多少页) currentPage(现在是第几页)
*/
self.pageControl.numberOfPages = self.pageSum;
//设置代理对象
self.scrollView.delegate = self;
//设置scrollView可视区域的宽度
CGSize imgViewSize = self.scrollView.frame.size;
self.scrollVisibleW = imgViewSize.width;
/*
第一种方法
NSTimeInterval 每隔多少时间
target: 调用一次X的
selector: XX方法
userInfo: 发送XX消息
repeats: 是否重复
*/
self.timerImgScroll = [NSTimer scheduledTimerWithTimeInterval: 2.0 target:self selector: @selector(autoImgScoll) userInfo:nil repeats:YES];
//获取当前运行的线程,将’计时器’添加到当前线程,调整当前线程的优先等级
NSRunLoop *currentLoop = [NSRunLoop currentRunLoop];
[currentLoop addTimer:self.timerImgScroll forMode:NSRunLoopCommonModes];
}
//自动实现轮播
-(void)autoImgScoll{
self.pageNo ++;
if(self.pageNo >= self.pageSum){
self.pageNo = 0;
}
CGFloat offsetScroll = (CGFloat)self.pageNo * self.scrollVisibleW;
self.scrollView.contentOffset = CGPointMake(offsetScroll, 0);
}
/*
开始拖动,(计时器销毁)
*/
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{
NSLog(@"计时器销毁...");
[self.timerImgScroll invalidate];
}
/*
结束拖动
*/
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
NSLog(@"开启timerBlock计时器...");
/*
第二种,使用block方式
当前的页数*scrollView可视宽度 = 需要移动的偏移量
timer - block:满足block里面的条件,方执行timer! 不满足则不执行timer
*/
self.timerImgScroll = [NSTimer scheduledTimerWithTimeInterval:2.0 repeats:YES block:^(NSTimer * _Nonnull timer) {
self.pageNo++;
if (self.pageNo >= self.pageSum) {
self.pageNo = 0;
}
CGFloat offsetScroll = (CGFloat)self.pageNo * self.scrollVisibleW;
self.scrollView.contentOffset = CGPointMake(offsetScroll, 0);
}];
//获取当前运行的线程,将’计时器’添加到当前线程,调整当前线程的优先等级
NSRunLoop *currentLoop = [NSRunLoop currentRunLoop];
[currentLoop addTimer:self.timerImgScroll forMode:NSRunLoopCommonModes];
}
/*
监听滚动事件
通过偏移量,来计算出滚动到某个宽度,则PageControl跳转到下一个
计算公式: (滚动的偏移量 + 每页宽度*0.5)/每页的宽度 = 第几页
计算公式: 滚动的偏移量/每页的宽度 + 0.5 = 第几页
*/
- (void)scrollViewDidScroll:(UIScrollView *)scrollView{
NSLog(@"%@",NSStringFromCGPoint(self.scrollView.contentOffset));
//获取滚动时的偏移量
self.scrollOffset = self.scrollView.contentOffset;
//self.pageNo = scrollOffset.x/self.scrollVisibleW;
//最初方法没有*0.5,这样如果将图片滚动到中间位置,pageControl不会改变为下一页(就是那个点,不会改变)!
//self.pageNo = self.scrollOffset.x /self.scrollVisibleW;
self.pageNo = (self.scrollOffset.x + self.scrollVisibleW *0.5)/self.scrollVisibleW;
self.pageControl.currentPage = self.pageNo;
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
}
@end
