Apple's New Swift Language - Basic info

• Swift is a new language designed by Apple for developing iOS and OS X applications.
• It takes the best parts of C and Objective-C and adapts them with modern features and patterns. Swift-compiled programs will run on iOS7 or newer and OS X 10.9 (Mavericks) or newer.
• The two main goals for the language are compatibility with the Cocoa and Cocoa Touch frameworks and safety, as you’ll see in the upcoming chapters. If you’ve been using Objective-C, especially the modern syntax, Swift will feel familiar.
• However, Swift’s syntax is actually a major departure from Objective-C. It takes lots of cues from programming languages such as Haskell, C#, Ruby, and Python.

    Improvements over Objective-C

    Type Inference 

• you can figure out the type of the variable by the value it is assigned. There is usually no need to specify the type of variables , the types of the variables can be inferred by the value being set. 

    Type Safety

• Swift variables must have a type and must be initialized before they can be used. Conversion between different types is done explicitly; you cannot simply assign a float to an integer.
• let doubleValue : Double = floatValue // This is an error

    Control Flow

• The switch statement has undergone a major overhaul. Now it can select based not only integers, but also on strings, floats, and ranges of items, expressions, enums, and so forth. Moreover, there’s no implicit fall-through between case statements.
• Also introduced a guard statement. A guard statement is like an if statement but with an additional requirement of always having an else statement. 

    Optionals

• A variable will either be nil or it will have a valid value. The nil value is distinct from any valid value. Optionals can also be chained together to protect against errors and exceptions. 

    Unicode

• The String and Character types are also fully Unicode compliant and support various encodings, such as  UTF-8, UTF-16, and 21-bit Unicode scalers.

    Other Improvements

• Header files are no longer required.
• Functions are full-fledged objects; they can be passed as arguments and returned from other functions. Functions can be scoped similarly to instance variables.
• Comments can be nested.
• There are separate operators for assignment (=) and comparison (==), and there’s even an identity operator (===) for checking whether two data elements refer to the same object.
• There is no defined entry point for programs such as main.