如何使用或不使用ScrollView使ImageView可缩放。 [英] how to make an ImageView zoomable with or without ScrollView.?

问题描述

我的 IB 中有 UImageView ，并在 UImageView上添加了地图图片。我想让那个图像捏缩放。

I have an UImageView in my IB and added a map image on that UImageView. I want to make that image pinch zoomable.

这是我的代码：

- (void)viewDidLoad
{
   [super viewDidLoad];
    self.title = @"Map";

   self.mapImageView.contentMode = UIViewContentModeScaleAspectFit;
   [self.mapScrollView addSubview:self.mapImageView];
   [self.mapScrollView setContentSize:CGSizeMake(self.mapImageView.frame.size.width, self.mapImageView.frame.size.height)];
   [self.mapScrollView setMinimumZoomScale:1.0];
   [self.mapScrollView setMaximumZoomScale:4.0];
}

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
   return self.mapImageView;
}

但这没有帮助，我可以看到 UIScrollView 即将发生，但我的形象没有任何变化。

提前致谢。

but this doesn't help, I can see a UIScrollView Coming but nothing happen to my image.
Thanks in advance.

推荐答案

在 ViewController.h 文件中添加 UIScrollViewDelegate

然后将以下代码添加到 ViewController.m 文件

then add following code to your ViewController.m file

无需添加 UIPinchGestureRecognizer 如果您使用此代码

No need to add UIPinchGestureRecognizer if your using this code

    - (void)scrollViewDidZoom:(UIScrollView *)scrollView
    {

    UIView* zoomView = [scrollView.delegate viewForZoomingInScrollView:scrollView];

    CGRect zoomViewFrame = zoomView.frame;

    if(zoomViewFrame.size.width < scrollView.bounds.size.width)

    {

    zoomViewFrame.origin.x = (scrollView.bounds.size.width - zoomViewFrame.size.width) / 2.0;

    }

    else

    {
    zoomViewFrame.origin.x = 0.0;
    }

    if(zoomViewFrame.size.height < scrollView.bounds.size.height)

     {      zoomViewFrame.origin.y = (scrollView.bounds.size.height - zoomViewFrame.size.height) / 2.0;

    }
    else

    {
    zoomViewFrame.origin.y = 0.0;
    }
    zoomView.frame = zoomViewFrame;
    }

更改 viewDidLoad as关注

- (void)viewDidLoad
 {
     [super viewDidLoad];
    self.mapScrollView.delegate = self;
    self.mapScrollView.minimumZoomScale = 1.0;
    self.mapScrollView.maximumZoomScale = 4.0;
    UIImage * myImage= [UIImage imageNamed:@"Background.png"]; //add your image here
    [self.mapImageView setImage:myImage];
    [self.mapImageView sizeToFit];
    self.mapScrollView.contentSize = myImage.size;

}

指定imageView放大这里

Specify the imageView to zoom here

- (UIView*)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
    return self.mapImageView;
}

为了避免在zoomimg上使用UIScrollView的奇怪行为，请使用此方法

To avoid the strange behaviour of UIScrollView on zoomimg use this method

- (void)view:(UIView*)view setCenter:(CGPoint)centerPoint
{
    CGRect viewFrame = view.frame;
        CGPoint contentOffset = self.mapScrollView.contentOffset;

        CGFloat x = centerPoint.x - viewFrame .size.width / 2.0;
        CGFloat y = centerPoint.y - viewFrame .size.height / 2.0;

    if(x < 0)
    {
        contentOffset.x = -x;
        viewFrame .origin.x = 0.0;
    }
    else
    {
        viewFrame .origin.x = x;
    }
    if(y < 0)
    {
        contentOffset.y = -y;
        viewFrame .origin.y = 0.0;
    }
    else
    {
        viewFrame .origin.y = y;
    }

    view.frame = viewFrame ;
    self.mapScrollView.contentOffset = contentOffset;
}

然后在viewDidAppear上调用上述方法

Then call the above method on viewDidAppear

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    CGPoint centerPoint = CGPointMake(CGRectGetMidX(self.mapScrollView.bounds),
                                  CGRectGetMidY(self.mapScrollView.bounds));
    [self view:self.mapImageView setCenter:centerPoint];
}

看看这个 link 如果您需要更多说明。我从那个链接学到了这个技术。

have a look at this link if you need more clarification. I learned this technique from that link.

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