Question

在Apple的page control sample中，界面构建器中有一个ScrollView。它与相应的IBOutlet相关联。我想更改代码，所以这一切都是以编程方式完成的。我删除了界面构建器对象，删除了IBOutlet关键字。我分配并初始化scrollView，但是当我运行程序时没有出现。

我认为这是因为我需要将它作为子视图分配给主视图。或者我呢？我仍然不太了解所有观点是如何工作和相互作用的。如果我[self.view addSubView:ScrollView];我收到运行时错误（或者其他东西，它通常只是说BAD ACCESS或SIGABRT）。

我做错了什么？我完全走错了路吗？（只有两天的ios编程，在树林里仍然有点迷失）

手机内容控制器中的

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

的appDelegate：

#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

并且已从xib文件中删除了scrollView。注意：这是下载程序的新版本，我所做的就是删除scrollView的IBOutlet关键字，从xib中删除滚动，并从nib中清醒地添加alloc，init行。

我已经建议更改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

由于您未从nib文件加载界面，因此应使用UIScrollView的{{1}}方法设置PhoneContentController：

init

在- (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; }中，进行以下更改：

AppDelegate

Answer 2

你只需将它放在awakeFromNib方法

中

scrollView=[[UIScrollView alloc] initWithFrame:CGRectMake(0, 20, 320, 440)];

无需添加为子视图，因为在phoneContentController xib中没有视图。所以如何添加像[self.view addSubView：ScrollView];这是因为phoneContentController不是UIViewController类的类型。它是ContentController的一个子类，它是该项目中NSObject的子类。

Answer 3

简单方法：如果需要手段，可以多次创建

- (void)viewDidLoad
{
    [super viewDidLoad];

    int x = 0;
    int y = 10;
    for(int i=0; i<5; i++)
    {
        UIScrollView *scrollview=[[UIScrollView alloc]initWithFrame:CGRectMake(x, y, 50, 50)];
        scrollview.showsVerticalScrollIndicator=YES;
        scrollview.scrollEnabled=YES;
        scrollview.userInteractionEnabled=YES;
        scrollview.backgroundColor = [UIColor greenColor];
        [self.view addSubview:scrollview];
        //scrollview.contentSize = CGSizeMake(50,50);
        x=x+55;

        //[self myscrollView];
    }
}

以编程方式实现UIScrollView

3 个答案: