(iOS) Storyboard없이 오브젝트 넣을때 유용한 메서드(anchor)

• descriptionTextView.topAnchor.constraint 와 같이 top,bottom,leading,triling등을 다 코드로 상속 시켜줘야하는데 anchor메서드를 사용하면 descriptionTextView.anchor(top : ,right : ,...) 으로 간편하게 할 수 있다.

extension UIView {
    
    func anchor(top: NSLayoutYAxisAnchor? = nil, left: NSLayoutXAxisAnchor? = nil, bottom: NSLayoutYAxisAnchor? = nil, right: NSLayoutXAxisAnchor? = nil, paddingTop: CGFloat? = 0,
                paddingLeft: CGFloat? = 0, paddingBottom: CGFloat? = 0, paddingRight: CGFloat? = 0, width: CGFloat? = nil, height: CGFloat? = nil) {
        
        translatesAutoresizingMaskIntoConstraints = false
        
        if let top = top {
            topAnchor.constraint(equalTo: top, constant: paddingTop!).isActive = true
        }
        
        if let left = left {
            leftAnchor.constraint(equalTo: left, constant: paddingLeft!).isActive = true
        }
        
        if let bottom = bottom {
            if let paddingBottom = paddingBottom {
                bottomAnchor.constraint(equalTo: bottom, constant: -paddingBottom).isActive = true
            }
        }
        
        if let right = right {
            if let paddingRight = paddingRight {
                rightAnchor.constraint(equalTo: right, constant: -paddingRight).isActive = true
            }
        }
        
        if let width = width {
            widthAnchor.constraint(equalToConstant: width).isActive = true
        }
        
        if let height = height {
            heightAnchor.constraint(equalToConstant: height).isActive = true
        }
    }
}

//사용 예시

followButton.anchor(top: topAnchor, right: rightAnchor,
                             paddingTop: 64, paddingRight: 32, width: 32, height: 32)
                             
//이 메서드가 없었더라면?
descriptionTextView.topAnchor.constraint(equalTo: bearImageView.bottomAnchor, constant: 50).isActive = true
        descriptionTextView.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
        descriptionTextView.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
        descriptionTextView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: 300).isActive = true


// 4번 적을거를 한번만 적어주면된다.