UIScrollView代理方法调用时间

示例代码

#import "ViewController.h"

@interface ViewController ()<UIScrollViewDelegate>
@property(nonatomic,strong)UIScrollView *scrollView;
@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    self.scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(40, 40, 320, 460)];
    self.scrollView.backgroundColor = [UIColor redColor];
    // 是否支持滑动最顶端
    //    self.scrollView.scrollsToTop = NO;
    self.scrollView.delegate = self;
    // 设置内容大小，即滚动范围
   self.scrollView.contentSize = CGSizeMake(320, 700);
    // 是否反弹
    //    self.scrollView.bounces = NO;
    // 是否分页
    //    self.scrollView.pagingEnabled = YES;
    // 是否滚动
    //    self.scrollView.scrollEnabled = NO;
    //    self.scrollView.showsHorizontalScrollIndicator = NO;
    // 设置indicator风格
    //    self.scrollView.indicatorStyle = UIScrollViewIndicatorStyleWhite;
    // 设置内容的边缘和Indicators边缘
    //    self.scrollView.contentInset = UIEdgeInsetsMake(0, 50, 50, 0);
    //    self.scrollView.scrollIndicatorInsets = UIEdgeInsetsMake(0, 50, 0, 0);
    // 提示用户,Indicators flash
    [self.scrollView flashScrollIndicators];
    // 是否同时运动,lock
    self.scrollView.directionalLockEnabled = YES;
    [self.view addSubview:self.scrollView];
    
    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 200, 320, 40)];
    label.backgroundColor = [UIColor yellowColor];
    label.text = @"学习UIScrolleview";
    // 文字居中
    label.textAlignment = NSTextAlignmentCenter;
    [self.scrollView addSubview:label];
}

#pragma mark -
/*
 // 返回一个放大或者缩小的视图
 - (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
 {
 
 }
 // 开始放大或者缩小
 - (void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:
 (UIView *)view
 {
 
 }
 
 // 缩放结束时
 - (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale
 {
 
 }
 
 // 视图已经放大或缩小
 - (void)scrollViewDidZoom:(UIScrollView *)scrollView
 {
 NSLog(@"scrollViewDidScrollToTop");
 }
 */

// 是否支持滑动至顶部
- (BOOL)scrollViewShouldScrollToTop:(UIScrollView *)scrollView
{
    return YES;
}

// 滑动到顶部时调用该方法
- (void)scrollViewDidScrollToTop:(UIScrollView *)scrollView
{
    NSLog(@"scrollViewDidScrollToTop");
}

/*************************************缓慢拖动、快速拖动都会调用************************************/
// scrollView 开始拖动(刚有拖动的迹象就调用,即在调用scrollViewDidScroll之前就会调用scrollViewWillBeginDragging方法)
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
    NSLog(@"scrollViewWillBeginDragging");
}
// scrollView 已经滑动(拖动就调用，只要你不停的拖动，这个方法就会调用无数次)
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    NSLog(@"scrollViewDidScroll");
}

// scrollView 结束拖动(松开鼠标停止拖动的那一瞬间调用(水平滚动ScrollView也调用，垂直滚动TableView也调用))
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
    NSLog(@"scrollViewDidEndDragging");
}

/************************************快速拖动才会调用*********************************************/
// scrollView 开始减速(必须得有快速拖动的动作，立马停止拖动就会调用。如果是缓慢拖动，停止拖动时不会调用这个方法)
- (void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView
{
    NSLog(@"scrollViewWillBeginDecelerating");
}

// scrollview 减速停止(必须得有快速拖动的动作，scrollView滚动完毕(速度减为0)并且手已经松开的时候调用)
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    NSLog(@"scrollViewDidEndDecelerating"); 
}
@end

效果

• 缓慢拖动，快速拖动都会调用

  
  
  101.112.gif

• 快速拖动才会调用，因为只有快速拖动，减速的效果才明显

  
  
  101.113.gif

关键代码

/****************缓慢拖动、快速拖动都会调用*************/
// scrollView 开始拖动(刚有拖动的迹象就调用,即在调用scrollViewDidScroll之前就会调用scrollViewWillBeginDragging方法)
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
    NSLog(@"scrollViewWillBeginDragging");
}
// scrollView 已经滑动(拖动就调用，只要你不停的拖动，这个方法就会调用无数次)
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    NSLog(@"scrollViewDidScroll");
}

// scrollView 结束拖动(松开鼠标停止拖动的那一瞬间调用(水平滚动ScrollView也调用，垂直滚动TableView也调用))
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
    NSLog(@"scrollViewDidEndDragging");
}

/********************快速拖动才会调用********************/
// scrollView 开始减速(必须得有快速拖动的动作，立马停止拖动就会调用。如果是缓慢拖动，停止拖动时不会调用这个方法)
- (void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView
{
    NSLog(@"scrollViewWillBeginDecelerating");
}

// scrollview 减速停止(必须得有快速拖动的动作，scrollView滚动完毕(速度减为0)并且手已经松开的时候调用)
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    NSLog(@"scrollViewDidEndDecelerating"); 
}