Part of our job as developers is taking in a large amount of information and parsing it down to the components needed. I’ve always loved filtering and sorting through lists whether in excel or Salesforce or other content management systems. In my previous jobs, it was common to get a request like “We need a list of all the donors who gave more than $10,000 in the 2013 Fiscal Year under the age 45.” or “We need a list of 8th graders who live in Brooklyn.” I would then use a series of filters to parse down a database of donors or students into a usable result like a list of names and mailing addresses.
This post is a short cheatsheet on how to sort through data in dictionaries and arrays in Swift. In a future post, I will cover the unique steps needed to filter through JSONs.
Types of Sorting
Based on the information you have and what you need, there are different methods you can use to get your desired output. Below are some helpful methods to have in your toolbox when dealing with dictionaries.
filter: Greater Than or Less Than
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| //Greater Than or Less Than | |
| var rentPerMonth = [["rent" : 2200], ["rent" : 2350], ["rent" : 2300], ["rent" : 2490]] | |
| var filteredRent = rentPerMonth.filter({ | |
| $0["rent"] < 2000 | |
| }) | |
| print(filteredRent) |
This will display an empty array.
filter: Used for
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| //Select nonchanging values like neighbordhoods – Good for buttons | |
| let neighborhoods: NSArray = ["Crown Heights", "Clinton Hill", "Sunset Park"] | |
| let fiteredNeighborhoods = (neighborhoods as! Array).filter { $0 == "Sunset Park" } | |
| print(fiteredNeighborhoods) |
containsString: Search by Keyword
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| //Search by Keyword | |
| let savedApartments = [ | |
| "apt1" : "The unit comes with stainless steel appliances, a full-sized refrigerator, plenty of storage, a gas oven, a gas range, and a dishwasher.The bedroom has hardwood floors and a window that opens.", "apt2" : "you will love it", "apt3" : "So many great amenities"] | |
| for (name, description) in savedApartments { | |
| if description.containsString("a window that opens") { | |
| print(name) | |
| } | |
| } |
Shea Furey-King 
Leave a Reply