依据性能需求，实现iOS幻灯片切换功能。
1.图片少的情况下
Demo:https://github.com/shileseal/SLCarouselDemo
#import "ViewController.h"
@interfaceViewController ()<UIScrollViewDelegate>
@property (weak, nonatomic) IBOutletUIScrollView *scrollView;
@property (weak, nonatomic) IBOutletUIPageControl *pageControl;
@property (nonatomic, strong) NSTimer *timer;
@end
@implementation ViewController
- (void)viewDidLoad {
[superviewDidLoad];
CGFloat imageW = self.scrollView.frame.size.width;
CGFloat imageH = self.scrollView.frame.size.height;
CGFloat imageY = 0;
NSInteger number = 5;
for (int i = 0; i < 5; i++) {
UIImageView *imageView = [[UIImageViewalloc]init];
NSString *imageUrl = [NSStringstringWithFormat:@"%d",i];
NSLog(@"%@",imageUrl);
imageView.image = [UIImageimageNamed:imageUrl];
CGFloat imageX = i * imageW;
imageView.frame = CGRectMake(imageX, imageY, imageW, imageH);
self.scrollView.showsHorizontalScrollIndicator = NO;
[self.scrollViewaddSubview:imageView];
}
CGFloat contentW = number * imageW;
self.scrollView.contentSize = CGSizeMake(contentW, 0);
self.scrollView.pagingEnabled = YES;
self.scrollView.delegate = self;
[selfaddTimer];
}
- (void)nextImage {
int page = (int)self.pageControl.currentPage;
if (page == 4){
page = 0;
} else {
page ++;
}
CGFloat x = page * self.scrollView.frame.size.width;
self.scrollView.contentOffset = CGPointMake(x, 0);
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
NSLog(@"滚动中");
CGFloat scrollviewW = scrollView.frame.size.width;
CGFloat x = self.scrollView.contentOffset.x;
int page = (x + scrollviewW/2)/scrollviewW;
self.pageControl.currentPage = page;
}
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
[selfremoveTimer];
}
- (void)addTimer {
self.timer = [NSTimerscheduledTimerWithTimeInterval:1target:selfselector:@selector(nextImage) userInfo:nilrepeats:YES];
}
- (void)removeTimer {
[self.timerinvalidate];
}
@end
2.图片多的情况下，使用UICollectionView进行复用
Demo:https://github.com/shileseal/SLScrollViewReuseDemo
#import "ViewController.h"
@interfaceViewController ()<UICollectionViewDataSource,UICollectionViewDelegate>
@property (weak, nonatomic) IBOutletUICollectionView *collectionView;
@end
staticNSString *identifier = @"cell";
@implementation ViewController
- (void)viewDidLoad {
[superviewDidLoad];
self.collectionView.delegate = self;
self.collectionView.dataSource = self;
[self.collectionViewregisterClass:[UICollectionViewCellclass] forCellWithReuseIdentifier:identifier];
}
#pragma mark - UICollectionViewDataSource
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
return1;
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
return50;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifierforIndexPath:indexPath];
NSString *imageUrl = [NSStringstringWithFormat:@"%ld.png",(long)indexPath.row];
NSLog(@"%@",imageUrl);
UIImageView *imageView = [[UIImageViewalloc]initWithImage:[UIImageimageNamed:imageUrl]];
#warning 为什么这么写就无法显示呢？
// UIImageView *imageView = [[UIImageView alloc]init];
// imageView.image = [UIImage imageNamed:imageUrl];
[cell addSubview:imageView];
[cell bringSubviewToFront:imageView];
switch (indexPath.row%2) {
case1:
cell.backgroundColor = [UIColorwhiteColor];
break;
default:
cell.backgroundColor = [UIColorblueColor];
break;
}
NSLog(@"%@",cell);
return cell;
}
@end