What should image sizes be at @1x, @2x and @3x in Xcode?

Swift: Create Facebook Live Stream Animation

물결치는 하트와 엄지척 만들기

drand48()   –  0-1 random 숫자 만들기

CAKeyFrameAnimation

UIBezierPath

CAMediaTimingFunction

Swift: Create Facebook’s Image Zooming Animation using Core Animation

my review point is 8/10

https://youtu.be/kzdI2aiTX4k?t=29m45s   navigation bar를 덮는 view 만들어 적용하기 

https://youtu.be/kzdI2aiTX4k?t=32m25s   tab bar를 덮는 view를 만들적용하기 

Swift: Loading Images Asynchronously and storing with NSCache and NSURLCache

my review point is 9/10

https://youtu.be/BIgqHLTZ_a4?t=1m55s   getting image from url ( NSURLSession.sharedSession().dataTaskWithURL )

https://youtu.be/BIgqHLTZ_a4?t=7m18s   개발자가 만들어 사용하는 image caching example

https://youtu.be/BIgqHLTZ_a4?t=10m45s   memory low warning hook ( didReceiveMemoryWarning )

https://youtu.be/BIgqHLTZ_a4?t=11m30s   apple에서 제공하는 NSCache를 이용한 caching 작업

https://youtu.be/BIgqHLTZ_a4?t=13m45s   url작업은 기본 cache 기능이 있는데 이 기준치를 변경하는 방법 ( NSURLCache )

Swift: How to create Facebook News Feed (Part 1) – UICollectionView, NSLayoutConstraint

my review point is 8/10

https://youtu.be/NJxb7EKXF3U?t=13m40s   extension for better adding constraints

https://youtu.be/NJxb7EKXF3U?t=17m32s   스타일이 다른 두 스트링을 한번에 처리하는 경우 ( NSMutableAttributedString , appendAttributedString , 레이블obj.numberOfLines , NSMutableParagraphStyle)

attributed string에는 작은 이미지를 덧붙일수 있다.

https://youtu.be/NJxb7EKXF3U?t=21m29s   attachment를 string 에 덧붙이기 ( NSTextAttachment )

Swift: Firebase 3 – How to Play Videos with AVPlayer (Ep 21)

my review point is 10/10

https://youtu.be/4ISMTG-E3Po?t=2m28s   image view에 플레이 버튼 만들기 

https://youtu.be/4ISMTG-E3Po?t=5m54s   button에 image 넣기 ( 버튼obj.setImage() , 이미지obj.tintColor()  )

https://youtu.be/4ISMTG-E3Po?t=11m54s   play button 클릭시 플레이 구현하기

https://youtu.be/4ISMTG-E3Po?t=15m6s   연달아서 optional unwrap 하기 

https://youtu.be/4ISMTG-E3Po?t=14m10s   avplayer 를 이용 동영상 플레이하기 ( AVPlayerLayer , 유아임뷰obj.layer.addSublayer()  )

https://youtu.be/4ISMTG-E3Po?t=19m33s   스크롤시 avplayer의 플레이 내용이 다른 cell에 디스플레이 되는 것을 해결하는 방법 ( prepareForReuse )

https://youtu.be/4ISMTG-E3Po?t=22m10s   avplayer pause 

https://youtu.be/4ISMTG-E3Po?t=23m56s   when play button is clicked, progress spinner is spinning. make spinner ( UIActivityIndicatorView , 액티버티인디케이터obj.startAnimating )

Swift: Firebase 3 – How to Send Videos (Ep 20)

my review point is 9/10

https://youtu.be/eRkpdRDYGeM?t=3m20s   image picker controller에서 video도 선택 가능하게 하는 과정 ( mediaTypes )

https://youtu.be/eRkpdRDYGeM?t=6m9s   getting media file url ( UIImagePickerControllerMediaURL ) 

https://youtu.be/eRkpdRDYGeM?t=7m18s   firebase에 file upload , media file upload 

https://youtu.be/eRkpdRDYGeM?t=9m   firebase에서 file 다운로드 경로 구하기 ( donwloadURL()?.absoluteString )

https://youtu.be/eRkpdRDYGeM?t=13m40s   checking progress , observing task ( observeStatus , progress?.completedUnitCount)

https://youtu.be/eRkpdRDYGeM?t=20m15s   getting image from video file ( AVAssetImageGenerator ,  AVAsset , copyCGImageAtTime)