iOS

Enums An enum is considered as a structured data type that can be modified without needing to change say a String or Int multiple times within your code, for example the below shows how easy it would be to change something by accident and forget to change it somewhere else. let myString = "test" if myString == "ttest" { // Doesn't execute because "ttest" is the value assigned to "myString" } With a enum we can avoid this and never have to worry about changing the same thing more than once enum MyEnum : String { case Test = "test" } let enumValue = MyEnum . Test if enumValue == MyEnum . Test { // Will execute because we can reassign the value of "MyEnum.Test" unless we do so within "MyEnum" } Structs I'm not sure how much you know about the MVC pattern but in Swift this is a common practise, before I explain how structs are useful I'll...

Database Core Data Primary function is storing and fetching data Primary function is graph management (although reading and writing to disk is an important supporting feature) Operates on data stored on disk (or minimally and incrementally loaded) Operates on objects stored in memory (although they can be lazily loaded from disk) Stores "dumb" data Works with fully-fledged objects that self-manage a lot of their behavior and can be subclassed and customized for further behaviors Can be transactional, thread-safe, multi-user Non-transactional, single threaded, single user (unless you create an entire abstraction around Core Data which provides these things) Can drop tables and edit data without loading into memory Only operates in memory Perpetually saved to disk (and often crash resilient) Requires a save process Can be slow to create millions of new rows Can create millions of new objects in-memory very quickly (although saving these objects will be slow) Offer...

SQLite 3 Procedure & Functions iOS - SQLite Database SQLite can be used in iOS for handling data. It uses sqlite queries, which makes it easier for those who know SQL. Steps Involved Step 1.  Create a simple  View based application . Step 2.  Select your project file, then select targets and then add  libsqlite3.dylib  library in choose frameworks. Step 3.  Create a new file by selecting File-> New -> File... -> select  Objective C class  and click next. Step 4.  Name the class as  DBManager  with  "sub class of"  as NSObject. Step 5.  Select create. Step 6.  Update  DBManager.h  as follows − SQLite 3 Functions Preview sqlite3_open : This function is used to create and open a database file. It accepts two parameters, where the first one is the database file name, and the second a handler to the database. If the file does n...

Closures are self contained chunks of code that can be passed around and used in your code. Closures can capture and store references to any constants or variables from the context in which they are defined. This is know as closing over those variables, hence the name closures. Closures are use intensively in the Cocoa frameworks – which are used to develop iOS or Mac applications. Functions are a special kind of closures. There are three kinds of closures: global functions  – they have a name and cannot capture any values nested functions  – they have a name and can capture values from their enclosing functions closure expressions  – they don’t have a name and can capture values from their context The thing to keep in mind for the moment is that you already have an intuition about closures. They are almost the same as functions but don’t necessarily have a name. // a closure that has no parameters and return a String var hello: () -> ( String ) = { ...