Update Constraint.swift to import UIKit or AppKit
Update Constraint.swift to import UIKit or AppKit

Resolve a compiler error: "Use of undeclared type 'NSLayoutConstraint'"

rankun203/Cartography,fullstackclub/Cartography,ernestopino/Cartography,Khan/Cartography,cnbin/Cartography,eeschimosu/Cartography,eeschimosu/Cartography,sai43/Cartography,ken0nek/Cartography,cogddo/Cartography,cnbin/Cartography,ppamorim/Cartography,PiersonBro/Cartography,jessesquires/Cartography,LiuDeng/Cartography,xBrux/Cartography,bzmario/Cartography,dougbeal/Cartography,brunov0id/Cartography,seyton/Cartography,alvivi/Cartography,noluyo/Cartography,vinod1988/Cartography,vinod1988/Cartography,alvivi/Cartography,kliu/Cartography,gaurav1981/Cartography,msdgwzhy6/Cartography,seyton/Cartography,petester42/Cartography,ArthurKK/Cartography,dougbeal/Cartography,lixiaohu1990/Cartography,bzmario/Cartography,iosyoujian/Cartography,iosyoujian/Cartography,TimothyChilvers/Cartography,msdgwzhy6/Cartography,zilaiyedaren/Cartography,tonyli508/Cartography,TimothyChilvers/Cartography,ken0nek/Cartography,u10int/Cartography,rankun203/Cartography,linchanlau/Cartography,KyoheiG3/Cartography,tonyli508/Cartography-IOS7,ppamorim/Cartography,bestwpw/Cartography,linchanlau/Cartography,sai43/Cartography,lixiaohu1990/Cartography,cogddo/Cartography,petester42/Cartography,xBrux/Cartography,jessesquires/Cartography,Khan/Cartography,bestwpw/Cartography,ArthurKK/Cartography,brunov0id/Cartography,LiuDeng/Cartography,kliu/Cartography,noluyo/Cartography,u10int/Cartography,ernestopino/Cartography,tonyli508/Cartography-IOS7,gaurav1981/Cartography,tonyli508/Cartography,zilaiyedaren/Cartography,fullstackclub/Cartography,KyoheiG3/Cartography,PiersonBro/Cartography