IOS UIImageView has something like Android WRAP_CONTENT

Question

this is my code

    m_containerbackground = [UIView new];
    m_containerbackground.backgroundColor = [AppleColor clearColor];
    [m_containerbackground setTranslatesAutoresizingMaskIntoConstraints:NO];
    [self.view addSubview:m_containerbackground];
    
    [m_containerbackground.centerXAnchor constraintEqualToAnchor:self.view.centerXAnchor].active = YES;
    [m_containerbackground.centerYAnchor constraintEqualToAnchor:self.view.centerYAnchor].active = YES;
    [m_containerbackground.widthAnchor constraintEqualToConstant:width/pointScale].active = YES;
    [m_containerbackground.heightAnchor constraintEqualToConstant:height/pointScale].active = YES;

    m_container = [UIView new];
    [m_container setTranslatesAutoresizingMaskIntoConstraints:NO];
    [m_containerbackground addSubview:m_container];
    [m_container.centerXAnchor constraintEqualToAnchor:self.view.centerXAnchor].active = YES;
    [m_container.centerYAnchor constraintEqualToAnchor:self.view.centerYAnchor].active = YES;
    [m_container.widthAnchor constraintEqualToAnchor:m_containerbackground.widthAnchor].active = YES;
    [m_container.heightAnchor constraintEqualToAnchor:m_containerbackground.heightAnchor].active = YES;
    
    m_image = [AppleImageView new];
    [m_image setTranslatesAutoresizingMaskIntoConstraints:NO];
    m_image.image = m_srcImage;
    m_image.contentMode = UIViewContentModeScaleAspectFit;
    [m_container addSubview:m_image];
    [m_image.topAnchor constraintEqualToAnchor:m_container.topAnchor constant:topm].active = YES;
    [m_image.leadingAnchor constraintEqualToAnchor:m_container.leadingAnchor constant:leftm].active = YES;
    [m_image.trailingAnchor constraintEqualToAnchor:m_container.trailingAnchor constant:-rightm].active = YES;
    [m_image sizeToFit];

As shown in the code above, I am able to control the width of the m_image and I set the UIViewContentModeScaleAspectFit, this is because I want the width of the m_srcImage to scale to the same width as the m_image and the height of the m_srcImage to be scaled to the original aspect ratio . Then I want the height of the m_image to be the same as the height of the scaled m_srcImage, how do I do this?

Below is my Android code, this works under Android because Android has WRAP_CONTENT and the IOS heightAnchor constraintEqualToConstant can only set specific values...

m_image = new ImageView(m_activity);
        m_image.setId(m_image.hashCode());
        m_image.setImageBitmap(m_srcImage);
        m_image.setScaleType(ImageView.ScaleType.FIT_START);
        m_image.setAdjustViewBounds(true);
        m_container.addView(m_image);
        {
            ConstraintSet set = new ConstraintSet();
            set.clone(m_container);
            set.constrainHeight(m_image.getId(), ConstraintSet.WRAP_CONTENT);
            set.constrainWidth(m_image.getId(), ConstraintSet.MATCH_CONSTRAINT);
            set.connect(m_image.getId(), ConstraintSet.TOP, ConstraintSet.PARENT_ID, ConstraintSet.TOP,topm);
            set.connect(m_image.getId(), ConstraintSet.RIGHT, ConstraintSet.PARENT_ID, ConstraintSet.RIGHT,rightm);
            set.connect(m_image.getId(), ConstraintSet.LEFT, ConstraintSet.PARENT_ID, ConstraintSet.LEFT,leftm);
            set.applyTo(m_container);
        }

score 1 · Accepted Answer · answered Jul 23 '21 at 16:47

Here, You need to calculate the image height like this:

    CGFloat imgWidth = width / pointScale;
    CGFloat imgHeightExpect = m_srcImage.size.height * imgWidth/ m_srcImage.size.width;
    if (m_srcImage.size.width > imgWidth) {
        [m_image.heightAnchor constraintEqualToConstant:imgHeightExpect].active = YES;
    } else {
        [m_image.heightAnchor constraintEqualToConstant:imgHeightExpect].active = NO;
    }

You just add that code to the below your code.

Or you can reference other solutions at this link: How to resize UIImageView based on UIImage's size/ratio in Swift 3?

IOS UIImageView has something like Android WRAP_CONTENT

1 Answers1