iPhone Dev-页面控制 - scrollViewDidScroll没有触发

Question

我是iPhone开发的新手,正在研究这个教程:http://www.iosdevnotes.com/2011/03/uiscrollview-paging/#comment-25166 - 但我在XCode 4.3.2中这样做.这个例子非常简单,我理解代码,但由于某种原因,我的ViewController.m中没有为我启动scrollViewDidScroll函数(因此不会更改页面控件分页图标并将其更新到当前页面).我在这个函数中放置了一个NSLog(),所以我可以判断它是否曾经激活 - 但在我的调试控制台中我从未看到过这个文本

我的ViewController.h中的代码是:

 #import <UIKit/UIKit.h>

 @interface ViewController : UIViewController <UIScrollViewDelegate> {
     UIScrollView* scrollView;
     UIPageControl* pageControl;

 }

 @property (nonatomic, retain) IBOutlet UIScrollView* scrollView;
 @property (nonatomic, retain) IBOutlet UIPageControl* pageControl;

 @end

我的ViewController.m中的代码是:

 #import "ViewController.h"
 @implementation ViewController
 @synthesize scrollView, pageControl;

 // Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
 - (void)viewDidLoad {
     [super viewDidLoad];


NSArray *colors = [NSArray arrayWithObjects:[UIColor redColor], [UIColor greenColor], [UIColor blueColor], nil];
for (int i = 0; i < colors.count; i++) {
    CGRect frame;
    frame.origin.x = self.scrollView.frame.size.width * i;
    frame.origin.y = 0;
    frame.size = self.scrollView.frame.size;

    UIView *subview = [[UIView alloc] initWithFrame:frame];
    subview.backgroundColor = [colors objectAtIndex:i];
    [self.scrollView addSubview:subview];
    [subview release];
}

self.scrollView.contentSize = CGSizeMake(self.scrollView.frame.size.width * colors.count, self.scrollView.frame.size.height);

self.pageControl.currentPage = 0;
self.pageControl.numberOfPages = colors.count;
 }


 //!!!!!!!!!!!!!!
 //THIS IS WHERE MY PROBLEM IS -- THIS CODE DOESN'T SEEM TO EVER GET RUN EVEN WHEN I SCROLL!!!!!
 //!!!!!!!!!!!!!
 - (void)scrollViewDidScroll:(UIScrollView *)sender {
     NSLog(@"this just fired");

     // Switch the indicator when more than 50% of the previous/next page is visible
     CGFloat pageWidth = self.scrollView.frame.size.width;
     int page = floor((self.scrollView.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
     self.pageControl.currentPage = page;
 }


 - (void)didReceiveMemoryWarning {
     [super didReceiveMemoryWarning];
 }

 - (void)viewDidUnload {
    self.scrollView = nil;
    self.pageControl = nil;
 }


 - (void)dealloc {
     [scrollView release];
     [pageControl release];
     [super dealloc];
 }

 @end

任何帮助将不胜感激.我一直在他们在教程上的可下载文件来回反复...我只是觉得当我开始滚动并且不知道它为什么不是......提前致谢!

Answer 1

在Interface Builder中,您没有将滚动视图的"委托"插座连接到视图控制器.但是你可以通过编程方式完成它.

[self.scrollView setDelegate:self];