textfield 자간
https://stackoverflow.com/questions/31877002/how-to-set-letter-spacing-of-uitextfield
navigationbar 뒤로가기 back button 없어지는 문제
https://stackoverflow.com/questions/919832/uinavigationcontrollers-back-button-disappears
customize modal size
https://stackoverflow.com/questions/54737884/changing-the-size-of-a-modal-view-controller
https://www.wwdcnotes.com/notes/wwdc14/228/
init(frame:)
vs. required init?(coder aDecoder: NSCoder)
vs. awakeFromNib()
https://ios-development.tistory.com/222
https://memohg.tistory.com/58
https://stackoverflow.com/questions/6906631/iboutlet-isnt-connected-in-awakefromnib
UILable corner radius
https://dongkyprogramming.tistory.com/15
tableview upper extra space
https://stackoverflow.com/questions/18880341/why-is-there-extra-padding-at-the-top-of-my-uitableview-with-style-uitableviewst
collectionview dynamic size
https://stackoverflow.com/questions/23134986/dynamic-cell-width-of-uicollectionview-depending-on-label-width
collectionview prevent multiple selection
https://stackoverflow.com/questions/39588474/deselect-a-collectionview-cell-when-another-cell-is-selected
추상화 = 의미의 단위화
https://soojin.ro/blog/solid-principles-in-swift
개방 폐쇄 원칙 (Open Closed Principle)를 지키는 방법
https://medium.com/swift-fox/refactoring-replace-enum-with-polymorphism-c4803baeba07
Notification Pattern VS. Delegation Pattern
https://medium.com/@Alpaca_iOSStudy/delegation-notification-그리고-kvo-82de909bd29
https://shinesolutions.com/2011/06/14/delegation-notification-and-observation/
리퀘스트 url 보는 방법
https://nareunhagae.tistory.com/m/75
