iphone - 以编程方式实现 UIScrollView

Question

在page control sample来自苹果的界面生成器中有一个 ScrollView。它与相应的 IBOutlet 链接。我想更改代码，以便全部以编程方式完成。我删除了界面生成器对象，我删除了 IBOutlet 关键字。我分配并初始化了 scrollView，但是当我运行程序时什么也没有出现。

我假设这是因为我需要将它作为 subview 分配给主视图。或者我呢？我仍然不太了解所有 View 如何工作以及如何相互作用。如果我执行 [self.view addSubView:ScrollView]; 我会收到一个运行时错误(或者其他什么，它通常只是说 BAD ACCESS 或 SIGABRT)。

我做错了什么？我完全走错了路吗？ (只接触 ios 编程两天，仍然有点迷失在树林里)

手机内容 Controller 中的 awakeFromNib:

- (void)awakeFromNib
{
scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];

// load our data from a plist file inside our app bundle
NSString *path = [[NSBundle mainBundle] pathForResource:@"content_iPhone" ofType:@"plist"];
self.contentList = [NSArray arrayWithContentsOfFile:path];

// view controllers are created lazily
// in the meantime, load the array with placeholders which will be replaced on demand
NSMutableArray *controllers = [[NSMutableArray alloc] init];
for (unsigned i = 0; i < kNumberOfPages; i++)
{
    [controllers addObject:[NSNull null]];
}
self.viewControllers = controllers;
[controllers release];

// a page is the width of the scroll view
scrollView.pagingEnabled = YES;
scrollView.contentSize = CGSizeMake(scrollView.frame.size.width * kNumberOfPages,  scrollView.frame.size.height);
scrollView.showsHorizontalScrollIndicator = NO;
scrollView.showsVerticalScrollIndicator = NO;
scrollView.scrollsToTop = NO;
scrollView.delegate = self;

pageControl.numberOfPages = kNumberOfPages;
pageControl.currentPage = 0;

// pages are created on demand
// load the visible page
// load the page on either side to avoid flashes when the user starts scrolling
//
[self loadScrollViewWithPage:0];
[self loadScrollViewWithPage:1];
}

头文件:

#import <UIKit/UIKit.h>
#import <Foundation/Foundation.h>

#import "ContentController.h"

@interface PhoneContentController : ContentController <UIScrollViewDelegate>
{   
UIScrollView *scrollView;
UIPageControl *pageControl;
NSMutableArray *viewControllers;

// To be used when scrolls originate from the UIPageControl
BOOL pageControlUsed;
}

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

@property (nonatomic, retain) NSMutableArray *viewControllers;

- (IBAction)changePage:(id)sender;

@end

应用委托(delegate):

#import "AppDelegate.h"
#import "ContentController.h"

@implementation AppDelegate

@synthesize window, contentController;

- (void)dealloc
{
[window release];
[contentController release];

[super dealloc];
}

- (void)applicationDidFinishLaunching:(UIApplication *)application
{
NSString *nibTitle = @"PadContent";
if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone)
{
    nibTitle = @"PhoneContent";
}
[[NSBundle mainBundle] loadNibNamed:nibTitle owner:self options:nil];

[self.window addSubview:self.contentController.view];
[window makeKeyAndVisible];
}

@end

并且 scrollView 已从 xib 文件中删除。注意:这是下载程序的新版本，我所做的所有更改是删除了 scrollView 的 IBOutlet 关键字，从 xib 中删除了 scroll 并添加了 alloc，init line in awake from nib。

我有建议更改 appDelegate 并将 awakeFromNib 更改为 init 方法，我已经尝试了所有这些但它仍然不起作用。

Answer 1

由于您不是从 nib 文件加载界面，因此您应该在 PhoneContentController 的 init 方法中设置您的 UIScrollView :

- (id)init
{
    [super init];

    if (self) {
        scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 20, 320, 440)];
        pageControl = [[UIPageControl alloc] initWithFrame:CGRectMake(<#CGFloat x#>, <#CGFloat y#>, <#CGFloat width#>, <#CGFloat height#>)]; // Place it where you want it.
        viewControllers = [[NSMutableArray alloc] init];

        // load our data from a plist file inside our app bundle
        NSString *path = [[NSBundle mainBundle] pathForResource:@"content_iPhone" ofType:@"plist"];
        self.contentList = [NSArray arrayWithContentsOfFile:path];

        // view controllers are created lazily
        // in the meantime, load the array with placeholders which will be replaced on demand
        NSMutableArray *controllers = [[NSMutableArray alloc] init];
        for (unsigned i = 0; i < kNumberOfPages; i++)
        {
            [controllers addObject:[NSNull null]];
        }
        self.viewControllers = controllers;
        [controllers release];

        // a page is the width of the scroll view
        scrollView.pagingEnabled = YES;
        scrollView.contentSize = CGSizeMake(scrollView.frame.size.width * kNumberOfPages, scrollView.frame.size.height);
        scrollView.showsHorizontalScrollIndicator = NO;
        scrollView.showsVerticalScrollIndicator = NO;
        scrollView.scrollsToTop = NO;
        scrollView.delegate = self;

        pageControl.numberOfPages = kNumberOfPages;
        pageControl.currentPage = 0;

        // pages are created on demand
        // load the visible page
        // load the page on either side to avoid flashes when the user starts scrolling
        //
        [self loadScrollViewWithPage:0];
        [self loadScrollViewWithPage:1];
    }

    return self;
}

在您的 AppDelegate 中，进行以下更改:

- (void)applicationDidFinishLaunching:(UIApplication *)application
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone) {
        contentController = [[PhoneContentController alloc] init];
    } else {
        contentController = [[PadContentController alloc] init];
    }

    [self.window addSubview:contentController.view];
    [window makeKeyAndVisible];
}