UIView+SizeConstraints.Swift

gistfile1.txt

import Foundation

extension UIView {
  func height(constant: CGFloat) {
    setConstraint(value: constant, attribute: .height)
  }
  
  func width(constant: CGFloat) {
    setConstraint(value: constant, attribute: .width)
  }
  
  private func removeConstraint(attribute: NSLayoutAttribute) {
    constraints.forEach {
      if $0.firstAttribute == attribute {
        removeConstraint($0)
      }
    }
  }
  
  private func setConstraint(value: CGFloat, attribute: NSLayoutAttribute) {
    removeConstraint(attribute: attribute)
    let constraint =
      NSLayoutConstraint(item: self,
                         attribute: attribute,
                         relatedBy: NSLayoutRelation.equal,
                         toItem: nil,
                         attribute: NSLayoutAttribute.notAnAttribute,
                         multiplier: 1,
                         constant: value)
    self.addConstraint(constraint)
  }
}

Updated to Swift 5

extension UIView {
  func height(constant: CGFloat) {
    setConstraint(value: constant, attribute: .height)
  }
  
  func width(constant: CGFloat) {
    setConstraint(value: constant, attribute: .width)
  }
  
    private func removeConstraint(attribute: NSLayoutConstraint.Attribute) {
    constraints.forEach {
      if $0.firstAttribute == attribute {
        removeConstraint($0)
      }
    }
  }
  
    private func setConstraint(value: CGFloat, attribute: NSLayoutConstraint.Attribute) {
    removeConstraint(attribute: attribute)
    let constraint =
      NSLayoutConstraint(item: self,
                         attribute: attribute,
                         relatedBy: NSLayoutConstraint.Relation.equal,
                         toItem: nil,
                         attribute: NSLayoutConstraint.Attribute.notAnAttribute,
                         multiplier: 1,
                         constant: value)
    self.addConstraint(constraint)
  }
}