如何在 ScrollView (iPhone) 中启用缩放

Posted 2023-03-16

【中文标题】如何在 ScrollView (iPhone) 中启用缩放

【英文标题】：How to enable Zooming in ScrollView (iPhone)

【发布时间】：2011-03-17 22:13:32

【问题描述】：

我有一个代码，我想修改它以获得缩放功能。现在我的应用只做水平滚动而不做缩放。

我错过了一些东西，因为我尝试了“viewForZoomingInScrollView：”但没有成功。 我怎样才能放大这个？

谢谢

#import <UIKit/UIKit.h>

@interface IntroductionViewController : UIViewController <UIScrollViewDelegate>
    IBOutlet UIScrollView *scrollView;

    CGRect rectScrollView;

    int scrollWidth;  
    int scrollHeight;  

    NSArray *contentArray; 

    UIColor *bcgColor; 

    BOOL rememberPosition;  
    NSString *positionIdentifier;



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

/// returns width of the scollview  
- (int)getScrollViewWidth;  

/// set width and height for your final UIScrollView  
- (void)setWidth:(int)width andHeight:(int)height;  

/// set the exactly same size as it is your parent view  
- (void)setSizeFromParentView:(UIScrollView *)scView;  

/// set background color for your UIScrollView  
- (void)setBackGroudColor:(UIColor *)color;  

/// set an array with images you want to display in your new scroll view  
- (void)setContentArray:(NSArray *)images; 

/// enable position history  
- (void)enablePositionMemory;  

/// enable position history with custom memory identifier  
- (void)enablePositionMemoryWithIdentifier:(NSString *)identifier;  

/// returns your UIScrollView with predefined page  
- (UIScrollView *)getWithPosition:(int)page;  

/// returns your UIScrollView with enabled position history  
- (UIScrollView *)getWithPositionMemory;  

/// returns your UIScrollView with enabled position history with custom memory identifier  
- (UIScrollView *)getWithPositionMemoryIdentifier:(NSString *)identifier;  

/// returns your UIScrollView  
- (UIScrollView *)get;  


@end

和实施：

#import "IntroductionViewController.h"


#define kIGUIScrollViewImagePageIdentifier                      @"kIGUIScrollViewImagePageIdentifier"  
#define kIGUIScrollViewImageDefaultPageIdentifier               @"Default"  

@implementation IntroductionViewController

@synthesize scrollView;


- (int)getScrollViewWidth   
    return ([contentArray count] * scrollWidth);  


- (void)setWidth:(int)width andHeight:(int)height   
    scrollWidth = width;  
    scrollHeight = height;  
    if (!width || !height) rectScrollView = [[UIScreen mainScreen] applicationFrame];  
    else rectScrollView = CGRectMake(0, 0, width, height);  


- (void)setSizeFromParentView:(UIScrollView *)scView   
    scrollWidth = scView.frame.size.width;  
    scrollHeight = scView.frame.size.height;  
    rectScrollView = CGRectMake(0, 0, scrollWidth, scrollHeight);  
  

- (void)setContentArray:(NSArray *)images   
    contentArray = images;


- (void)setBackGroudColor:(UIColor *)color   
    bcgColor = color;  
  


- (void)enablePositionMemoryWithIdentifier:(NSString *)identifier   
    rememberPosition = NO;  
    if (!identifier) identifier = kIGUIScrollViewImageDefaultPageIdentifier;  
    positionIdentifier = identifier;  
  

- (void)enablePositionMemory   
    [self enablePositionMemoryWithIdentifier:nil];  


- (UIScrollView *)getWithPosition:(int)page   
    if (!contentArray)   
        contentArray = [[[NSArray alloc] init] autorelease];  
      
    if (page > [contentArray count]) page = 0;  

    if (!scrollWidth || !scrollHeight)   
        rectScrollView = [[UIScreen mainScreen] applicationFrame];  
        scrollWidth = rectScrollView.size.width;  
        scrollHeight = rectScrollView.size.height;  
      
    rectScrollView = CGRectMake(0, 0, scrollWidth, scrollHeight);  

    self.scrollView = [[UIScrollView alloc] initWithFrame:rectScrollView];  
    self.scrollView.contentSize = CGSizeMake([self getScrollViewWidth], scrollHeight);  
    if (!bcgColor) bcgColor = [UIColor blackColor];  
    self.scrollView.backgroundColor = bcgColor;  
    self.scrollView.alwaysBounceHorizontal = YES;  
    self.scrollView.contentOffset = CGPointMake(page * scrollWidth, 0);  
    self.scrollView.pagingEnabled = YES;  


    UIView *main = [[[UIView alloc] initWithFrame:rectScrollView] autorelease];  
    int i = 0;  
    for (UIImage *img in contentArray)   
        UIImageView *imageView = [[UIImageView alloc] init];  
        imageView.image = img;
        imageView.contentMode = UIViewContentModeScaleAspectFit;  
        imageView.autoresizingMask = (UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight);  
        imageView.backgroundColor = [UIColor blackColor];  
        float ratio = img.size.width/rectScrollView.size.width;  
        CGRect imageFrame = CGRectMake(i, 0, rectScrollView.size.width, (img.size.height / ratio));  
        imageView.frame = imageFrame;
        [self.scrollView addSubview:(UIView *)imageView];  
        i += scrollWidth; 
        [imageView release];  
      
    [main addSubview:scrollView];


    //if (margin) [margin release];
    [self.scrollView release];
    [self.scrollView release];
    return (UIScrollView *)main;





- (UIScrollView *)get   
    return [self getWithPosition:0];  
  

- (UIScrollView *)getWithPositionMemory   
    [self enablePositionMemory];  
    return [self getWithPosition:[[[NSUserDefaults standardUserDefaults] objectForKey:[NSString stringWithFormat:@"%@%@", kIGUIScrollViewImagePageIdentifier, kIGUIScrollViewImageDefaultPageIdentifier]] intValue]];  


- (UIScrollView *)getWithPositionMemoryIdentifier:(NSString *)identifier   
    [self enablePositionMemoryWithIdentifier:identifier];  
    return [self getWithPosition:[[[NSUserDefaults standardUserDefaults] objectForKey:[NSString stringWithFormat:@"%@%@", kIGUIScrollViewImagePageIdentifier, positionIdentifier]] intValue]];  


- (void)scrollViewDidEndDecelerating:(UIScrollView *)sv   
    int page = sv.contentOffset.x / sv.frame.size.width;
    if (rememberPosition)   
        [[NSUserDefaults standardUserDefaults] setObject:[NSString stringWithFormat:@"%d", page] forKey:[NSString stringWithFormat:@"%@%@", kIGUIScrollViewImagePageIdentifier, positionIdentifier]];  
        [[NSUserDefaults standardUserDefaults] synchronize];  
      


- (NSArray *)getImages   
    NSMutableArray *arr = [[[NSMutableArray alloc] init] autorelease];

    // codice per intercettare la lingua impostata dall utente
    NSUserDefaults  *defaults  = [NSUserDefaults standardUserDefaults];
    NSArray         *languages  = [defaults objectForKey:@"AppleLanguages"];
    NSString    *currentLanguage  = [languages objectAtIndex:0];
    NSLog(@"Codice lingua %@", currentLanguage);

    if( [currentLanguage isEqualToString:@"es"] )
        [arr addObject:[UIImage imageNamed:@"image1-intro.jpg"]];  
        [arr addObject:[UIImage imageNamed:@"image2-intro.jpg"]];  
        [arr addObject:[UIImage imageNamed:@"image3-intro.jpg"]];
        [arr addObject:[UIImage imageNamed:@"image4-intro.jpg"]];
        [arr addObject:[UIImage imageNamed:@"image5-intro.jpg"]];
        [arr addObject:[UIImage imageNamed:@"image6-intro.jpg"]];
        return (NSArray *)arr;
    

    else 
        [arr addObject:[UIImage imageNamed:@"image1-intro.jpg"]];  
        [arr addObject:[UIImage imageNamed:@"image2-intro.jpg"]];  
        [arr addObject:[UIImage imageNamed:@"image3-intro.jpg"]];
        [arr addObject:[UIImage imageNamed:@"image4-intro.jpg"]];
        [arr addObject:[UIImage imageNamed:@"image5-intro.jpg"]];
        return (NSArray *)arr;
    



/*
 // The designated initializer.  Override if you create the controller programmatically and want to perform customization that is not appropriate for viewDidLoad.
 - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil 
 if ((self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil])) 
 // Custom initialization
 
 return self;
 
 */


// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.

- (void)viewDidLoad 
    [super viewDidLoad];

    //codice per mettere il titolo come immagine
    UIImage *titolo = [UIImage imageNamed: @"introTitle.png"];
    UIImageView *titoloView = [[UIImageView alloc] initWithImage: titolo];
    self.navigationItem.titleView = titoloView;


    IntroductionViewController *svimage = [[IntroductionViewController alloc] init];  
    [svimage setContentArray:[self getImages]];
    [svimage setSizeFromParentView:scrollView];
    [self.view addSubview:[svimage getWithPosition:0]];
    [svimage release];
    [titoloView release];


/*
 // Override to allow orientations other than the default portrait orientation.
 - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation 
 // Return YES for supported orientations
 return (interfaceOrientation == UIInterfaceOrientationPortrait);
 
 */

- (void)didReceiveMemoryWarning 
    NSLog(@"memoria view");
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];

    // Release any cached data, images, etc that aren't in use.

- (void)viewDidUnload 
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;



- (void)dealloc 
    [super dealloc];



@end

【问题讨论】：

请格式化您的代码。

【参考方案1】：

您在哪里实现 viewForZoomingInScrollView？ 它返回什么？

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
    return yourViewToBeZoomed; // 

编辑：

好的，所以，一般来说，使用此方法，您只需指定当用户在您的 scrollView 上使用广告移动 2 个手指时您必须滚动的内容...通常（但并非总是）它是 UIScrollView 本身的第一个子视图。 .

所以，如果是您的情况，请尝试以下代码：

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
    return [scrollView2.subviews objectAtIndex:0];

如果您添加了更多 subView 并且也想缩放它们，您最好不要直接将它们添加到您的 UIScrollView 而是添加到您的第一个 subView，这样它们就会随之缩放...

知乎，

卢卡

【讨论】：

在我放在这里的代码中没有，但这就是问题所在，我必须使用什么视图？ - (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView return ??; //

@andrea：好的，我正在添加一个新的编辑，在一两分钟内看看我的旧答案...... ciao

我试过- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView return [scrollView.subviews objectAtIndex:0]; ，但它没有工作它给了ma一个“本地声明”scrollView“隐藏实例变量。所以我试过- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView return [self.scrollView.subviews objectAtIndex:0]; NSLog(@"zoom"); 但它不起作用，它不能缩放

@andrea: 好的，它隐藏了它，因为你有一个同名的属性，你的代码应该可以工作，或者你可以更改方法的参数名称：(UIScrollView *)scrollView -> (UIScrollView *)scrollView2 并返回 [scrollView2.subviews objectAtIndex:0]; ...但是要检查是否调用了该方法，您必须将 NSLog 行放在 RETURN 行之前（“return”停止该方法）...

@andrea: PS：但是你的类中的所有其他 方法都被调用了吗（例如 scrollViewDidEndDecelerating）？

【参考方案2】：

您是否设置了最大缩放比例？无论是在代码中，还是在 IB 中……

【讨论】：

是的，但我的问题是我为图像创建了一个数组，然后将该数组放入 ViewDidLoad 中。当我必须使用这种方法时，我将在里面使用什么视图？ - (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView return XXX

【参考方案3】：

这有效，Photoscroller Apple 示例，它也使用了 Tiling，但您可以禁用它（竞争或只是禁用白线）。它还支持旋转。

这里是你可以使用普通图像而不是平铺的地方：

- (void)configurePage:(ImageScrollView *)page forIndex:(NSUInteger)index

    page.index = index;
    page.frame = [self frameForPageAtIndex:index];

    // Use tiled images

    /*
    [page displayTiledImageNamed:[self imageNameAtIndex:index]
                            size:[self imageSizeAtIndex:index]];
    */

    // To use full images instead of tiled images, replace the "displayTiledImageNamed:" call
    // above by the following line:
    [page displayImage:[self imageAtIndex:index]];

如果您想使用平铺（用于大图像）但不想看到白线，这里是代码（在 ImageScrollView 中）：

- (void)displayTiledImageNamed:(NSString *)imageName size:(CGSize)imageSize

    // clear the previous imageView
    [imageView removeFromSuperview];
    [imageView release];
    imageView = nil;

    // reset our zoomScale to 1.0 before doing any further calculations
    self.zoomScale = 1.0;

    // make a new TilingView for the new image
    imageView = [[TilingView alloc] initWithImageName:imageName size:imageSize];
    /*
    [(TilingView *)imageView setAnnotates:YES]; // ** remove this line to remove the white tile grid **
    */
    [self addSubview:imageView];

    self.contentSize = imageSize;
    [self setMaxMinZoomScalesForCurrentBounds];
    self.zoomScale = self.minimumZoomScale;