extension扩展属性

背景

在UICollectionView中的Cell展示UIImageView，同时绑定UITapGestureRecognizer事件，传值section 和 item

定义

extension UIImageView {
    private struct definestruct{
        static var defineSection:Int = 0
        static var defineItem:Int = 0
    }
    var definesection:Int{
        get{
            return objc_getAssociatedObject(self, &definestruct.defineSection) as! Int
        }
        set(value){
            objc_setAssociatedObject(self, &definestruct.defineSection, value, objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN_NONATOMIC)
        }
    }
    var defineitem:Int{
        get{
            return objc_getAssociatedObject(self, &definestruct.defineItem) as! Int
        }
        set(value){
            objc_setAssociatedObject(self, &definestruct.defineItem, value, objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN_NONATOMIC)
        }
    }
}

使用

imgview.definesection = indexPath.section
imgview.defineitem = indexPath.item