iOS开发UI篇—UIScrollView控件实现图片轮播
一、实现效果
实现图片的自动轮播
二、实现代码
storyboard中布局
代码：
#import "YYViewController.h" @interface YYViewController () <UIScrollViewDelegate>
@property (weak, nonatomic) IBOutlet UIScrollView *scrollview;
/**
* 页码
*/
@property (weak, nonatomic) IBOutlet UIPageControl *pageControl; @property (nonatomic, strong) NSTimer *timer;
@end @implementation YYViewController - (void)viewDidLoad
{
[super viewDidLoad]; // 图片的宽
CGFloat imageW = self.scrollview.frame.size.width;
// CGFloat imageW = 300;
// 图片高
CGFloat imageH = self.scrollview.frame.size.height;
// 图片的Y
CGFloat imageY = ;
// 图片中数
NSInteger totalCount = ;
// 1.添加5张图片
for (int i = ; i < totalCount; i++) {
UIImageView *imageView = [[UIImageView alloc] init];
// 图片X
CGFloat imageX = i * imageW;
// 设置frame
imageView.frame = CGRectMake(imageX, imageY, imageW, imageH);
// 设置图片
NSString *name = [NSString stringWithFormat:@"img_0%d", i + ];
imageView.image = [UIImage imageNamed:name];
// 隐藏指示条
self.scrollview.showsHorizontalScrollIndicator = NO; [self.scrollview addSubview:imageView];
} // 2.设置scrollview的滚动范围
CGFloat contentW = totalCount *imageW;
//不允许在垂直方向上进行滚动
self.scrollview.contentSize = CGSizeMake(contentW, ); // 3.设置分页
self.scrollview.pagingEnabled = YES; // 4.监听scrollview的滚动
self.scrollview.delegate = self; [self addTimer];
} - (void)nextImage
{
int page = (int)self.pageControl.currentPage;
if (page == ) {
page = ;
}else
{
page++;
} // 滚动scrollview
CGFloat x = page * self.scrollview.frame.size.width;
self.scrollview.contentOffset = CGPointMake(x, );
} // scrollview滚动的时候调用
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
NSLog(@"滚动中");
// 计算页码
// 页码 = (contentoffset.x + scrollView一半宽度)/scrollView宽度
CGFloat scrollviewW = scrollView.frame.size.width;
CGFloat x = scrollView.contentOffset.x;
int page = (x + scrollviewW / ) / scrollviewW;
self.pageControl.currentPage = page;
} // 开始拖拽的时候调用
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
// 关闭定时器(注意点; 定时器一旦被关闭,无法再开启)
// [self.timer invalidate];
[self removeTimer];
} - (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
// 开启定时器
[self addTimer];
} /**
* 开启定时器
*/
- (void)addTimer{ self.timer = [NSTimer scheduledTimerWithTimeInterval: target:self selector:@selector(nextImage) userInfo:nil repeats:YES];
}
/**
* 关闭定时器
*/
- (void)removeTimer
{
[self.timer invalidate];
}
@end
提示：以下两个属性已经和storyboard中的控件进行了连线。
@property (weak, nonatomic) IBOutletUIScrollView *scrollview;
@property (weak, nonatomic) IBOutletUIPageControl *pageControl;
补充：定时器NSTimer
定时器 适合用来隔一段时间做一些间隔比较长的操作
NSTimeInterval:多长多件操作一次
target :操作谁
selector : 要操作的方法
userInfo: 传递参数
repeats: 是否重复
self.timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(nextImage) userInfo:nil repeats:YES];