Swift, a quick overview

Swift, a quick overview

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  Swift, a quickoverview Julian Król iOS developer
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  Notice (!) Thispresentation can be not objective but subjective. Any opinions are highly appreciated ;)
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  General (vital 1/3) • no header files for classes, only implementation file (one .swift file) • no differentiation between ivar and property • no need for alloc/init • swift can ‘guess’ type of a variable according to the object a developer assigns to it (no need for an explicit type declaration)
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  General (vital 2/3) ! • added computed properties (computation at calling time) • added property observers (you can take some action when value changes to different value) • added keyword indicating for overriding method in subclass
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  General (vital 3/3) • structures can have functions • enums are not restricted to represent int values • extensions are improvement to categories (you can add functionality to structs and primitive types) • added generics - something like templates in C++
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  General (very discussable,maybe even not vital) • no semicolon at the end of the line • less syntax required (example: no need for parenthesis in if-statement) • easier operations on strings • printing to console do not require hard(er) formatting
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  switch statement •has to have a default statement • case do not need a break statement • case value can be whatever developer want • switch has to cover all possible values (requirement for default case if enlisting is impossible)
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  blocks -> closures • a bit easier syntax (block syntax was complex from time to time) • closures can be seen as unnamed functions • variables in closures are not copied but mutable
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  functions • parametercan have a default value (missed that when migrated from C++) • can return multiple values (I know obj-c can do this via arrays dictionaries or any other user’s object)
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  Extensions • Swiftequivalent to the Objective-C category • can add properties but they have to be computed one (see other types of properties) • can add protocol conformance to a class
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  Reasons why Swiftcan be a very safe language
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  Safety • arrayscan have only one type of objects • optionals ‘?’ for marking possibility of receiving/ returning a nil value • indication for type overflow
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  Safety • ifstatement has to have curly brackets ‘{}’ • switch has to cover all possible values • marking overridden functions
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  Safety • id-> AnyObject • dealing with unrecognised selector by adding ‘?’ to a method call
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  Comparison in Swift • ‘==‘ for objects equality • ‘===‘ for objects identity
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  Comparison in Swift • Comparison and Hashable protocols inherits from Equatable • Equatable needs an implementation of: func ==(leftSide: Self, rightSide: Self) -> Bool • Hashable needs an implementation of a getter for the hashValue property • Comparable needs those three: func <=(leftSide: Self, rightSide: Self) -> Bool func >(leftSide: Self, rightSide: Self) -> Bool func >=(leftSide: Self, rightSide: Self) -> Bool
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  Swift in Objective-C? YES! Possible! It is easy!
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  Swift in Objective-C Swift code prefixed with @objc can be accessed from Objective-C code except Swift specific features (tuples, generics etc.) No need for explicit @objc if Swift class inherits from the Objective-C one!
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  Swift & Objective-C Swift class can inherits from Objective-C one but not the other way round!
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  The End Incase of any suggestion and/or opinion drop me an email: viperking@poczta.onet.pl