ios 如何在 UIScrollView 中实现 scrollViewDidScroll
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How to implement scrollViewDidScroll in UIScrollView
提问by colindunn
I'm having a problem where when I call the scrollViewDidScrollmethod in my subclass of UIScrollViewnothing happens. Here is my code:
我遇到了一个问题，当我scrollViewDidScroll在我的子类中调用该方法时UIScrollView什么也没有发生。这是我的代码：
AppDelegate.m
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
滚动视图.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);
}
采纳答案by Tony Stark
in
在
- (id)initWithFrame:(CGRect)frame
add
添加
self.delegate = self;
or in AppDelegate.m,after scrollview inited, add this code
或在 AppDelegate.m 中，在滚动视图初始化后，添加此代码
scrollview.delegate = self;
of course, you must implements the delegate method
当然，你必须实现委托方法
scrollViewDidScroll:
and don't forgot add below code in AppDelegate.h
并且不要忘记在 AppDelegate.h 中添加以下代码
@interface AppDelegate : UIResponder <UIApplicationDelegate,UIScrollViewDelegate>
回答by ViJay Avhad
For iOS10, SWift 3.0 implement scrollViewDidScroll on UIScrollView
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.
}
}
回答by Suraj Sonawane
Step 1: Create Delegate for UIViewController Class:
第 1 步：为 UIViewController 类创建委托：
@interface ViewController : UIViewController <UIScrollViewDelegate>
Step 2: Then add Delegate for your UIScrollViewobject:
第 2 步：然后为您的UIScrollView对象添加委托：
scrollview.delegate = self;
Step 3: Implements Delegate methods as follow:
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
}
Here you go. With the help of above 3 steps you can integrate ScrollViewDidScrollmethod into our Objective-CClass.
干得好。借助以上 3 个步骤，您可以将ScrollViewDidScroll方法集成到我们的Objective-C类中。
