generics with swift
TRANSCRIPT
Generics with Swiftby akira hirakawa @akirahrkw
Do you Swift?
we use swift for Burpple app
Generics with Swift
Do you use Generics?
example
swap two Int valuesfunc swapTwoInts(inout a: Int, inout b: Int) {
let temporaryA = a
a = b
b = temporaryA
}
swap two Double valuesfunc swapTwoDoubles(inout a: Double, inout b: Double) {
let temporaryA = a
a = b
b = temporaryA
}
swap two String valuesfunc swapTwoStrings(inout a: String, inout b: String) {
let temporaryA = a
a = b
b = temporaryA
}
these are identical !!
more useful more flexible?
generics !!
Generic functionfunc swapTwoValues<T>(inout a: T, inout b: T) {
let temporaryA = a
a = b
b = temporaryA
}
swap Int valuesvar someInt = 3
var anotherInt = 107
swapTwoValues(&someInt, &anotherInt)
swap String valuesvar someString = "hello"
var anotherString = "world"
swapTwoValues(&someString, &anotherString)
can notvar someInt = 3
var anotherString = "world"
swapTwoValues(&someInt, &anotherString)
useful flexible
but
why not use Protocol?
can
swap two Any valuesfunc swapTwoValues(inout a: Any, inout b: Any) {
let temporaryA = a
a = b
b = temporaryA
}
var a = 1 as Any
var b = 2 as Any
swapTwoValues(&a, &b)
var a = “a” as Any
var b = “b” as Any
swapTwoValues(&a, &b)
but
var a = 1 as Any
var b = “a” as Any
swapTwoValues(&a, &b)
which is better?
what is the difference?
func executeProtocol(p: Printable) -> Printable {
}
func executeGenerics<T: Printable>(p: T) -> T {
}
almost same
func executProtocol(p: Printable) -> Printable {
p.description
return p
}
func executeGenerics<T: Printable>(p: T) -> T {
p.description
return p
}
no difference?
return value
func executProtocol(p: Printable) -> Printable {
return p
}
func executeGenerics<T: Printable>(p: T) -> T {
return p
}
-> Printableyou need to cast to use the return value
var movie: Movie = …
var p: Printable = executProtocol(movie)
(p as Movie).show()
-> Tyou don’t need to cast to use the value
var movie: Movie = …
movie = executeGenerics(movie)
movie.show()
useful
different
performance?
case swap method:
case increment:
depends on -O and swift version
fast useful
flexible
in practice?
case DataSource:
but
case DataSource:
Generics doesn’t work on TableViewDeleate, TableViewDataSource because of a bug
ds.respondsToSelector(“tableView:numberOfRowsInSection:”) is false
http://www.openradar.me/radar?id=5829206453780480
case API Call:
Request<T>
Request<[User]>
Object Mapper
AnyObject -> Tvar orm = { (json: AnyObject) -> User in … … return user
}
var orm = { (json: AnyObject) -> Media in … … return media
}
Completion Handler
T -> ()var handler = { ( item:User) -> () in … …
}
var handler = { (item:Media) -> () in … …
}
fast useful
flexible practical
I like generics :)
thanks
question?