iOS实现左右循环滑动ScrollVIew

作为iOS 开发的新手，前几天去一家公司比试，拿到了这个题。感觉挺简单（思路：构造一个scrollView 添加三个UIimageView，保持scrollview可见的区域一直是中间的那个image，当滑动结束的时候作判断，重新设置scrollview 可见区域的位置并且相应调整imageview的位置，这样就可以无限滑动了）。但是由于很长时间没用xcode了，之前一直作。net研发，（用macbook上机试，没有鼠标，我操作了一会儿感觉不爽，借鼠标，被鄙视。。。。）40分钟过完，没做好。面试官来问我做好没，我说有点问题需要调试，他看下对我说今天面试到此结束，如果需要进一步面试的话会通知我。。。

今天终于做上了iOS 研发，就先把这个功能实现，思路见上段。

代码：定义变量

@interface ViewController ()
{
UIImageView * imageView1;
UIImageView * imageView2;
UIImageView * imageView3;
UIImage * image1;//contents
UIImage * image2;
UIImage * image3;
}

ViewDidLoad：设置ScrollView和imageview

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
UIScrollView * scview = [[UIScrollView alloc] init];
scview.pagingEnabled = YES;
image1 = [UIImage imageNamed:@"test1.jpg"];
image2 = [UIImage imageNamed:@"test2.jpg"];
image3 = [UIImage imageNamed:@"test3.jpg"];
imageView1 = [[UIImageView alloc] initWithImage:image1];
imageView2 = [[UIImageView alloc] initWithImage:image2];
imageView3 = [[UIImageView alloc] initWithImage:image3];
imageView1.frame = CGRectMake(0, 0, 300, 300);
imageView2.frame = CGRectMake(300, 0, 300, 300);
imageView3.frame = CGRectMake(600, 0, 300, 300);
scview.contentSize = CGSizeMake(900, 300);
scview.frame = CGRectMake(0, 0, 300, 300);
[scview addSubview:imageView1];
[scview addSubview:imageView2];
[scview addSubview:imageView3];
[self.view addSubview:scview];
scview.contentOffset = CGPointMake(300, 0);
scview.delegate = self;
}

关键：需要在本控制器实现的协议<span style="color: rgb(112, 61, 170); font-family: Menlo; font-size: 14px;">UIScrollViewDelegate，并且实现方法</span>

-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
if(scrollView.contentOffset.x>=0&&scrollView.contentOffset.x<=10)//xiang you hua，关于设置一个范围因为调试的时候发现content offset.x有时候不是0，300，600
{
int x = imageView1.frame.origin.x + 300;
if(x>=900) x = 0;
imageView1.frame = CGRectMake(x, 0, imageView1.bounds.size.width, imageView1.bounds.size.height);
x = x+300;
if(x>=900) x = 0;
imageView2.frame = CGRectMake(x, 0, imageView1.bounds.size.width, imageView1.bounds.size.height);
x = x+300;
if(x>=900) x = 0;
imageView3.frame = CGRectMake(x, 0, imageView1.bounds.size.width, imageView1.bounds.size.height);
}
if (scrollView.contentOffset.x>=590&&scrollView.contentOffset.x<=610) {//向左划
int x = imageView1.frame.origin.x - 300;
if(x<0)
x = 600;
imageView1.frame = CGRectMake(x, 0, imageView1.bounds.size.width, imageView1.bounds.size.height);
x= x+300;
if(x>=900)x = 0;
imageView2.frame = CGRectMake(x, 0, imageView1.bounds.size.width, imageView1.bounds.size.height);
x= x+300;
if(x>=900)x = 0;
imageView3.frame = CGRectMake(x, 0, imageView1.bounds.size.width, imageView1.bounds.size.height);
}
scrollView.contentOffset = CGPointMake(300, 0);
}

思路挺简单的，先根据向左滑动，还是向右滑动确定imageview1的位置，然后imageview2，imageview3的位置就是依次x＋300，当然超过900的时候要设置为0