phone screen: 1) write a method to detect if a rectangle is inside another rectangle. takes 2 params. the first one is bigger, the 2nd one is smaller. both params are frame (CGRect). return boolean, next question is leetcode 408 onsite: 1) write a method to take two string of numbers with decimal. e.g. "12.892347823" and "65655.62". return the sum of these two numbers in string. CANNOT convert param into integer. similar to leetcode 415, but it is decimal numbers 2) write a Array extension method like func remove(removeArray: [Int]). this method remove the elements in removeArray from original array. e.g. array has [1,3,3,4,5,1,6], removeArray is [1, 3], the method removes 1 and 3 from original array, so it returns [4,5,6]. 3) leetcode 31 4) leetcode 1249 System design: design an app similar to IG, but user swipe horizontally, and the app can swipe autmatically every 10 secs if user is doing nothing. when user swipes to next photo, timer resets to zero. Also, if you friend has a news feed posted, server can push to your app. new item is inserted to the front of the queue. e.g., the app has items 1,2,3,4,5. when your friends posted item 6 and 7 and you are looking at item 1, , your app will have 1, 6, 7, 2, 3, 4, 5. need to find a way for server to push to the app. (websocket, polling, or push notification. i chose polling). needs to explain what you choose.