在網路上打滾多時,後來才發現其實 Apple Dev Center 上的範例就很好用了!真搞不懂我在亂花時間做什麼

建議先下載範例程式跑一下,看看這個東西的功能是不是你想要的,以下是一些筆記

  1. 將圖片做適當的縮放並擺在 UIScrollView 來呈現,並且可以放大縮小,此範例僅寫在 YourAppDelegate 中,以及讓 YourAppDelegate 要去回應 UIScrollViewDelegate 和新增一個函數 viewForZoomingInScrollView,並且請準備一張圖擺到 Resources 中(此例是 Googlelogo.png):

    @interface YourAppDelegate : NSObject <UIApplicationDelegate, UIScrollViewDelegate> {
        UIWindow *window;
        UIImageView *imageView ;
    }
    @property (nonatomic, retain) IBOutlet UIWindow *window;
    @end

    @implementation YourAppDelegate
    @synthesize window;

    - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    
        //UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Googlelogo.png"]];

        imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Googlelogo.png"]];
        UIScrollView *scrollView = [[UIScrollView alloc] init];
        [scrollView setFrame:[window frame]];
        [scrollView addSubview:imageView];
        [window addSubview:scrollView];
        //[imageView release];
        [scrollView release];

        CGFloat widthRatio = [scrollView frame].size.width / [imageView frame].size.width;
        CGFloat heightRatio = [scrollView frame].size.height / [imageView frame].size.height;
        CGFloat initialZoom = (widthRatio > heightRatio) ? heightRatio : widthRatio;
        
        [scrollView setZoomScale:initialZoom];
        [scrollView setMinimumZoomScale:initialZoom];
        [scrollView setMaximumZoomScale:2.0];

        CGSize imageViewAdjustSize = CGSizeMake([imageView frame].size.width * initialZoom, [imageView frame].size.height * initialZoom);
        [scrollView setContentSize:imageViewAdjustSize];
        
        [imageView setFrame:CGRectMake(0, 0, imageViewAdjustSize.width, imageViewAdjustSize.height)];
        [imageView setCenter:[scrollView  center]];
       
        [scrollView setDelegate:self];


        // Override point for customization after application launch
        [window makeKeyAndVisible];
        return YES;
    }

    - (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
    {
        return imageView;
    }


    - (void)dealloc {
        [imageView release];
        [window release];
        [super dealloc];
    }
    @end

    uiscrollview
  2. 在某些情境下,希望使用 UIScrollView 來提供 Paging 的效果,例如翻頁的效果,其觀念就是把 UIScrollView 的 Content Width 設成你要的 Page * Width 的寬度,接著設定一開始執行時要停在哪個 Page ,最後則是每一頁的內容要擺什麼,以下是修改 (1) 的程式碼,以 3 Page 為例,並把 UIScrollView 起始擺在第 2 頁,而真正的呈現的圖片擺在第 3 頁,所以執行的效果是,一開始畫面是空白的,但可以往右移過去,及翻到第 3 頁並看到圖片,接著往左可以移兩頁,但因為沒有設定內容,所以看到的都是空白的:

    - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    

        //UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Googlelogo.png"]];
        imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Googlelogo.png"]];
        UIScrollView *scrollView = [[UIScrollView alloc] init];
        [scrollView setFrame:[window frame]];
        [scrollView addSubview:imageView];
        [scrollView setDelegate:self];
        [window addSubview:scrollView];
        //[imageView release];
        [scrollView release];
        
        CGFloat widthRatio = [scrollView frame].size.width / [imageView frame].size.width;
        CGFloat heightRatio = [scrollView frame].size.height / [imageView frame].size.height;
        CGFloat initialZoom = (widthRatio > heightRatio) ? heightRatio : widthRatio;
        
        [scrollView setZoomScale:initialZoom];
        [scrollView setMinimumZoomScale:initialZoom];
        [scrollView setMaximumZoomScale:2.0];
        
        [imageView setFrame:CGRectMake(0, 0, [imageView frame].size.width * initialZoom, [imageView frame].size.height * initialZoom)];
        
        int TotalPageCount = 3;
        int MainImagePageOffset = 2;
        int CureentPageOffset = 1;

        // content width of scrollView = TotalPageCount * width of scrollView => paging
        CGSize imageViewAdjustSize = CGSizeMake( [scrollView frame].size.width * TotalPageCount, [scrollView frame].size.height );
        [scrollView setContentSize:imageViewAdjustSize];
        
        CGPoint imageOffsetOnScrollViewContent = [scrollView center];
        imageOffsetOnScrollViewContent.x += [imageView frame].size.width * MainImagePageOffset;
        [imageView setCenter:imageOffsetOnScrollViewContent];
        
        [scrollView setContentOffset:CGPointMake( [imageView frame].size.width * CureentPageOffset, 0 )];
        [scrollView setPagingEnabled:YES];


        // Override point for customization after application launch
        [window makeKeyAndVisible];
        
        return YES;
    }


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