UIButton Inside Header Not Working - xcode8

Question

I've been searching for this answer but can't seem to find it.
I have a sectionHeader above a collection view. I added a button into the header but the function doesn't run. Mind taking a quick look for 1min and helping me out?
import UIKit
class SearchHeader: UICollectionViewCell {
let filterLbl: UILabel = {
let label = UILabel()
label.text = "Filter"
label.font = UIFont.systemFont(ofSize: 18)
return label
}()
let addFilterBtn: UIButton = {
let button = UIButton(type: .system)
button.setImage(#imageLiteral(resourceName: "addFilter").withRenderingMode(.alwaysOriginal), for: .normal)
button.addTarget(self, action: #selector(handleAddFilter), for: .touchUpInside)
return button
}()
func handleAddFilter(button: UIButton) {
print(1234)
}
override init(frame: CGRect) {
super.init(frame: frame)
backgroundColor = .white
addSubview(filterLbl)
addSubview(addFilterBtn)
filterLbl.anchor(top: topAnchor, left: leftAnchor, bottom: bottomAnchor, right: nil, paddingTop: 10, paddingLeft: 10, paddingBottom: 10, paddingRight: 0, width: 0, height: 0)
addFilterBtn.anchor(top: topAnchor, left: filterLbl.rightAnchor, bottom: bottomAnchor, right: nil, paddingTop: 10, paddingLeft: 5, paddingBottom: 10, paddingRight: 0, width: 0, height: 0)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}

Answer 1

I found the answer.
lazy var addFilterBtn: UIButton = {
let button = UIButton(type: .system)
button.setImage(#imageLiteral(resourceName: "addFilter").withRenderingMode(.alwaysOriginal), for: .normal)
button.addTarget(self, action: #selector(handleAddFilter), for: .touchUpInside)
return button
}()
for some reason you have to change let into lazy var