MIN 和 MAX 宏的 Swift 等效

min and max are defined in Swift:

func max<T : Comparable>(x: T, y: T, rest: T...) -> T
func min<T : Comparable>(x: T, y: T, rest: T...) -> T

and used like so:

let min = min(1, 2)
let max = max(1, 2)

See this great writeup on documented & undocumented built-in functions in Swift.

As pointed out, Swift provides max and min functions.

An example (updated for Swift 2.x).

let numbers = [ 1, 42, 5, 21 ]
var maxNumber = Int()


for number in numbers {
maxNumber = max(maxNumber, number as Int)
}


print("the max number is \(maxNumber)")   // will be 42

With Swift 5, max(_:_:) and min(_:_:) are part of the Global Numeric Functions. max(_:_:) has the following declaration:

func max<T>(_ x: T, _ y: T) -> T where T : Comparable

You can use it like this with Ints:

let maxInt = max(5, 12) // returns 12

Also note that there are other functions called max(_:_:_:_:) and min(_:_:_:_:) that allows you to compare even more parameters. max(_:_:_:_:) has the following declaration:

func max<T>(_ x: T, _ y: T, _ z: T, _ rest: T...) -> T where T : Comparable

You can use it like this with Floats:

let maxInt = max(12.0, 18.5, 21, 26, 32.9, 19.1) // returns 32.9

With Swift however, you're not limited to use max(_:_:) and its siblings with numbers. In fact, those functions are generic and can accept any parameter type that conforms to Comparable protocol, may it be String, Character or one of your custom class or struct.

Thereby, the following Playground sample code works perfectly:

class Route: Comparable, CustomStringConvertible {


let distance: Int
var description: String {
return "Route with distance: \(distance)"
}


init(distance: Int) {
self.distance = distance
}


static func ==(lhs: Route, rhs: Route) -> Bool {
return lhs.distance == rhs.distance
}


static func <(lhs: Route, rhs: Route) -> Bool {
return lhs.distance < rhs.distance
}


}


let route1 = Route(distance: 4)
let route2 = Route(distance: 8)


let maxRoute = max(route1, route2)
print(maxRoute) // prints "Route with distance: 8"

Furthermore, if you want to get the min/max element of elements that are inside an Array, a Set, a Dictionary or any other sequence of Comparable elements, you can use the max() or the min() methods (see this Stack Overflow answer for more details).

Try this:

let numbers = [2, 3, 10, 9, 14, 6]
let min = numbers.min()
let max = numbers.max()
print("Max = \(max) Min = \(min)")

SWIFT 4 Syntax changed a bit:

public func max<T>(_ x: T, _ y: T) -> T where T : Comparable
public func min<T>(_ x: T, _ y: T) -> T where T : Comparable

and

public func max<T>(_ x: T, _ y: T, _ z: T, _ rest: T...) -> T where T : Comparable
public func min<T>(_ x: T, _ y: T, _ z: T, _ rest: T...) -> T where T : Comparable

So when you use it you should write like in this example:

let min = 0
let max = 100
let value = -1000


let currentValue = Swift.min(Swift.max(min, value), max)

So you get the value from 0 to 100 don't matter if is it below 0 or higher 100.