collectionview part2 swift

draw circle with beize
https://stackoverflow.com/questions/28442516/an-easy-way-to-draw-a-circle-using-cashapelayer
https://stackoverflow.com/questions/29616992/how-do-i-draw-a-circle-in-ios-swift

move constraint
https://stackoverflow.com/questions/30823325/how-to-move-a-uiview-programmatically-in-swift

updateview after set constraint  layoutIfNeeded()
https://stackoverflow.com/questions/31948123/determining-width-of-a-uiview-using-autolayout-swift
https://stackoverflow.com/questions/20590105/hot-to-get-uilabel-width-using-autolayout

determine screen size
https://stackoverflow.com/questions/24110762/swift-determine-ios-screen-size

draw line in circle
https://stackoverflow.com/questions/26662415/draw-a-line-with-uibezierpath

collectionview Header
https://stackoverflow.com/questions/21731318/add-a-simple-uiview-as-header-of-uicollectionview

rectangle with radius
https://stackoverflow.com/questions/30368739/how-to-draw-a-simple-rounded-rect-in-swift-rounded-corners

gradient layout again
https://stackoverflow.com/questions/37903124/set-background-gradient-on-button-in-swift