2020-09-10

随笔

scrollview的应用

@interface ViewController ()<UIScrollViewDelegate>

@property (nonatomic,assign) CGFloat itemWidth;

@property (nonatomic,assign) CGFloat offset;

@property (nonatomic,assign) CGFloat screenWidth;

@property (nonatomic,assign) CGFloat contentSizeWidth;

@property (nonatomic,assign) CGFloat position;

@end

- (void)viewDidLoad {

    [super viewDidLoad];

    CGFloatscreenWidth = [UIScreenmainScreen].bounds.size.width;

    self.screenWidth= screenWidth;

    CGFloatscrollX =0;

    CGFloatscrollW = screenWidth -2* scrollX;

    UIScrollView*scrollview = [[UIScrollViewalloc]initWithFrame:CGRectMake(scrollX ,100, scrollW,50)];

    scrollview.delegate=self;

    scrollview.bounces=NO;

    scrollview.showsVerticalScrollIndicator = NO;

    scrollview.showsHorizontalScrollIndicator = NO;

    scrollview.backgroundColor = [UIColor redColor];

    [self.viewaddSubview:scrollview];

    CGFloattargetViewX =0;

    CGFloattargetViewY =0;

    CGFloattargetViewW =300;

    CGFloattargetViewH =50;

    UIView*targetView = [[UIViewalloc]initWithFrame:CGRectMake(targetViewX, targetViewY, targetViewW, targetViewH)];

    targetView.backgroundColor = UIColor.blueColor;

    [scrollviewaddSubview:targetView];

    self.itemWidth= targetViewW;

    UIView*lineView = [[UIViewalloc]initWithFrame:CGRectMake(screenWidth/2.0-1,95,2,60)];

    lineView.backgroundColor = [UIColor greenColor];

    [self.viewaddSubview:lineView];

    CGFloatcontentSizeWidth =2* targetViewW + scrollW;

    self.contentSizeWidth= contentSizeWidth;

    scrollview.contentSize=CGSizeMake(contentSizeWidth, targetViewH);

    scrollview.contentOffset=CGPointMake(contentSizeWidth/2.0- screenWidth/2.0,0);

    CGFloatoffSet =  800;

    if(offSet <0) {

        offSet =0;

    }elseif(offSet >  self.itemWidth){

        offSet =self.itemWidth;

    }

    self.offset= offSet;

    targetViewX = contentSizeWidth/2- offSet;

    targetView.frame=CGRectMake(targetViewX, targetViewY, targetViewW, targetViewH);

    UIView*blackView = [[UIViewalloc]initWithFrame:CGRectMake(contentSizeWidth/2.0,0,2,50)];

    blackView.backgroundColor = [UIColor blackColor];

    [scrollviewaddSubview:blackView];

    UIView*lineView2 = [[UIViewalloc]initWithFrame:CGRectMake(0,25, scrollview.contentSize.width,3)];

    lineView2.backgroundColor = UIColor.whiteColor;

    NSLog(@"--scrollview.contentSize.width---%f",scrollview.contentSize.width);

    NSLog(@"--scrollview.contentSize.width---%f",scrollview.contentOffset.x);

    [scrollviewaddSubview:lineView2];

}

- (void)scrollViewDidScroll:(UIScrollView*)scrollView{

    NSLog(@"----%lf",scrollView.contentOffset.x);

    if(scrollView.contentOffset.x<=self.itemWidth-self.offset) {

        scrollView.contentOffset=CGPointMake(self.itemWidth-self.offset,0);

    }elseif(scrollView.contentOffset.x>  ((self.contentSizeWidth-self.screenWidth)/2.0+self.itemWidth-self.offset)){

        scrollView.contentOffset=CGPointMake((self.contentSizeWidth/2.0-self.screenWidth/2.0+self.itemWidth-self.offset),0);

    }

    self.position= scrollView.contentOffset.x;

}