UIScrollview，当完全缩小时是否可以在屏幕上移动视图？

Question

我试图弄清楚这是否可能。我的UIViewController（与屏幕大小相同）中有一个UIScrollView，设置的内容大小为640*640。滚动视图中的UIView，大小为 640 *640。代码：

#import "ViewController.h"

@interface ViewController () <UIScrollViewDelegate>

@property (weak, nonatomic) IBOutlet UIScrollView *scrollView;
@property (strong, nonatomic) UIView *viewForZoom;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    //self.profileImageView.layer.cornerRadius = self.profileImageView.frame.size.width / 2;
    //self.profileImageView.clipsToBounds = YES;


    UIView *content = [[[NSBundle mainBundle] loadNibNamed:@"floatingView" owner:self options:nil] objectAtIndex:0];
    self.viewForZoom=content; //need this pointer for the zoom
    self.scrollView.contentSize=CGSizeMake(640 ,640);

    self.scrollView.minimumZoomScale=0.25;
    self.scrollView.maximumZoomScale=1;

    [self.scrollView addSubview:content];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {

    return  self.viewForZoom;
}

这会按预期进行缩放和平移：

当完全缩小时，视图会停留在屏幕的左上角。我想要发生的是，当视图缩小时，它会粘在屏幕的中心，但它也可以在 640*640 容器内拖动。这是可能的吗？任何帮助，将不胜感激。谢谢

Answer 1

这非常有效。该方法来自 Apple 的 photoscroller 示例，它用于子类滚动视图（在 layoutSubviews 中）。我发现它在scrollViewDidZoom scrollView 委托方法中同样有效。

- (void)scrollViewDidZoom:(UIScrollView *)scrollView {
    CGSize boundsSize = self.scrollView.bounds.size;
    CGRect imageViewFrame = self.imageView.frame ;

    // centre horizontally
    if (imageViewFrame.size.width < boundsSize.width) {
        imageViewFrame.origin.x = (boundsSize.width - imageViewFrame.size.width) / 2;
    } else {
        imageViewFrame.origin.x = 0;
    }

    // centre vertically
    if (imageViewFrame.size.height < boundsSize.height && self.imageView.image) {
        imageViewFrame.origin.y = (boundsSize.height - imageViewFrame.size.height) / 2;
    } else {
        imageViewFrame.origin.y = 0;
    }
    self.imageView.frame = imageViewFrame;
}

编辑

看看questions，你有posted，我认为我没有充分解决这个问题以满足你的要求：

"但也可以在 640*640 的容器内拖动"