Using SnapKit to Aspect Ratio and less size

rafaeldepaula picture rafaeldepaula · Sep 11, 2019 · Viewed 7.8k times · Source

I am trying to create the constraints of this layout in SnapKit but I have difficulty setting the maximum size (lessThanOrEqual).

layout

let maxWidthContainer: CGFloat = 435
let maxHeightContainer: CGFloat = 600

containerView.snp.makeConstraints {
    $0.width.equalTo(containerView.snp.height).multipliedBy(maxWidthContainer / maxHeightContainer)
    $0.centerX.centerY.equalToSuperview()
    $0.leading.trailing.equalToSuperview().inset(38).priorityLow()
}

Answer

DonMag picture DonMag · Sep 11, 2019

If I understand what you're going for, this should do it:

    let v = UIView()
    v.backgroundColor = .blue
    view.addSubview(v)

    let maxWidthContainer: CGFloat = 435
    let maxHeightContainer: CGFloat = 600

    v.snp.makeConstraints { (make) in
        // centered X and Y
        make.centerX.centerY.equalToSuperview()

        // at least 38 points "padding" on all 4 sides

        // leading and top >= 38
        make.leading.top.greaterThanOrEqualTo(38)

        // trailing and bottom <= 38
        make.trailing.bottom.lessThanOrEqualTo(38)

        // width ratio to height
        make.width.equalTo(v.snp.height).multipliedBy(maxWidthContainer/maxHeightContainer)

        // width and height equal to superview width and height with high priority (but not required)
        // this will make it as tall and wide as possible, until it violates another constraint
        make.width.height.equalToSuperview().priority(.high)

        // max height
        make.height.lessThanOrEqualTo(maxHeightContainer)
    }