Developing iOS8 Hello World! Using Swift

Apple recently announced a pretty major change to the way iOS apps have been developed in the past, an entirely different programming language called Swift which replaces Objective-C. 
In my efforts to learn the new language, I’ve decided I will be posting regularly as I step through the learning process, sharing everything I find. This is the first post of many on the topic, and I hope you decide to follow along!

           

The Basics

Declaring Variables:

iOS8 Swift does away with the standard of declaring variables by starting with their type names, and instead opts to use a Javascript-like ‘var’ keyword to define any variable.

Objective-c: NSString *firstString=@"My first string";

Swift: var firstString="My first string"

Declaring Constants:

Objective-c: NSInteger *const myfirstconstant;

Swift: let ksomeconstant:int=10;

Meanwhile constants are expressed with the ‘let’ keyword.

Declaring arrays and dictionary:

Objective-c: NSArray *Myarray=[[NSArray alloc]init];

                    NSDictionary *Mydictionary=[[NSDictionary alloc]init];

Swift:   var Myarray=["one","two","three"]

            var Mydictionary=["primary number:one","secondary number:two"]

There’s a lot more to go over, but I think these basics are important to get a start going on to the tutorial. So with that, let’s move on to Hello World.

HELLO WORLD Program in Objective-c and Swift:

Objective-c:

#import

#import<Foundation/Foundation.h>

int main(void)

{

NSLog(@"Hello,World!\n");

return 0;

}

Swift:

1.Create a new x-code project in single view application.

2.Select SWIFT language.

3.Find AppDeligate.swift file inside the project

    Inside of this file find the line that says:

    “// Override point for customization after application launch.”

4.Replace this line with our amazing hello world code:

      println("Hello World")

Now press run and you should see a blank app boot up, and the words “Hello World” print to the console. Congratulations! You just wrote your first iOS8 Hello World application in Swift!