如何在UIScrollView中实现scrollViewDidScroll

我有一个问题，当我在UIScrollView子类中调用scrollViewDidScroll方法时，没有任何反应。 这是我的代码：

AppDelegate.m

 #import "ScrollView.h" - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]]; // Override point for customization after application launch. CGRect screenRect = [[self window] bounds]; ScrollView *scrollView = [[ScrollView alloc] initWithFrame:screenRect]; [[self window] addSubview:scrollView]; [scrollView setContentSize:screenRect.size]; self.window.backgroundColor = [UIColor whiteColor]; [self.window makeKeyAndVisible]; return YES; } 

ScrollView.m

 #import "AppDelegate.h" #import "ScrollView.h" - (id)initWithFrame:(CGRect)frame { self = [super initWithFrame:frame]; if (self) { // Initialization code NSString *imageString = [NSString stringWithFormat:@"image"]; UIImage *image = [UIImage imageNamed:imageString]; UIImageView *imageView = [[UIImageView alloc] initWithImage:image]; [super addSubview:imageView]; } return self; } - (void)scrollViewDidScroll:(UIScrollView *)scrollView { NSLog(@"%f", scrollView.contentOffset.y); } 

Answer 1

在

 - (id)initWithFrame:(CGRect)frame 

加

 self.delegate = self; 

或者在AppDelegate.m中，在scrollview inited之后，添加此代码

 scrollview.delegate = self; 

当然，您必须实现委托方法

 scrollViewDidScroll: 

并且不要忘记在AppDelegate.h中添加以下代码

 @interface AppDelegate : UIResponder  

Answer 2

第1步：为UIViewController类创建委托：

  @interface ViewController : UIViewController  

第2步：然后为您的UIScrollView对象添加Delegate：

  scrollview.delegate = self; 

第3步：实现Delegate方法如下：

  - (void)scrollViewDidScroll:(UIScrollView *)scrollView { // Do your stuff here... // You can also track the direction of UIScrollView here.... // to check the y position use scrollView.contentOffset.y } 

干得好。 在上述3个步骤的帮助下，您可以将ScrollViewDidScroll方法集成到我们的Objective-C类中。

Answer 3

对于iOS10，SWift 3.0在UIScrollView上实现scrollViewDidScroll

 class ViewController: UIViewController, UIScrollViewDelegate{ //In viewDidLoad Set delegate method to self. @IBOutlet var mainScrollView: UIScrollView! override func viewDidLoad() { super.viewDidLoad() self.mainScrollView.delegate = self } //And finally you implement the methods you want your class to get. func scrollViewDidScroll(_ scrollView: UIScrollView!) { // This will be called every time the user scrolls the scroll view with their finger // so each time this is called, contentOffset should be different. print(self.mainScrollView.contentOffset.y) //Additional workaround here. } }