Let say I got an array with Usr objects. And the Usr object have the attribute age. Except from reading the Usrobject one by one, and compare the age value one by one, is there any shortcuts to do so? Thx.
9 Answers
struct User {
var age: Int
}
let users = [ User(age: 10), User(age: 20), User(age: 30)]
let oldestUser = users.max { $0.age < $1.age }
oldestUser?.age // 30
answered Dec 19, 2016 at 6:38
Warif Akhand Rishi
24.3k8 gold badges82 silver badges109 bronze badges
1 Comment
Hamish
@toing_toing Why?
map alone returns an array of elements with a given transformation applied to them. max(by:) finds the maximum element in the sequence with a given predicate.You can simply map users array to array of user's age and the find max age:
class Usr {
var age: Int
init(_ age: Int) {
self.age = age
}
}
let users = [Usr(1), Usr(8), Usr(5)]
let maxAge = maxElement(users.map{$0.age}) // 8
4 Comments
nontomatic
Please note the new syntax for Swift 3: let maxAge = users.map { $0.age }.maxElement()
Kirsteins
Use max() instead of maxElement() in Swift 3.
nontomatic
Isn't max() for comparing 2 values as in: let x = max(2, 4)? The compiler will only accept arrayOfInts.maxElement().
Kirsteins
In Swift 3 you must use
arrayOfInts.max() in Swift 2 arrayOfInts.maxElement(). max() is variadic for 2 or more values.Swift 3:
let users = [Usr(15), Usr(25), Usr(20)]
let max = users.map { $0.age }.max()
// max = 25
Comments
Use max(by:) function
class Usr {
var age: Int
init(_ age: Int) {
self.age = age
}
}
let users = [Usr(3), Usr(8), Usr(6)]
if let userWithMaxAge : Usr = users.max(by: {$0.age < $1.age}){
print(userWithMaxAge.age)
}
It will print 8
Comments
The previous answers are a little mixed and don't exactly describe what I will achieve with the respecting approach. So, there are two different approaches, based on what you want.
If this is your model:
struct Purchase {
let id: String
let amount: Double
}
And these are your objects:
let iPhonePurchase = Purchase(id: "iPhone", amount: 999.00)
let iPadPurchase = Purchase(id: "iPad", amount: 1299.00)
let purchases = [iPhonePurchase, iPadPurchase]
If you want the object itself containing the highest value, use:
let highestPurchase = purchases.max { $0.amount < $1.amount }
This returns the object for iPadPurchase.
On the other hand, if you don't want to get the whole object, just the highest amount value:
let highestPurchase = purchases.map { $0.amount }.max()
Here you get 1299.00 as the highest value.
Comments
Other way:
class Usr {
var age: Int
init(_ age: Int) {
self.age = age
}
}
let users = [Usr(1), Usr(8), Usr(5)]
let largestAge = users.map{ $0.age }.reduce(0) { $0 > $1 ? $0 : $1 } // 8
answered Apr 17, 2016 at 16:53
Twitter khuong291
11.7k16 gold badges82 silver badges118 bronze badges
Comments
Another way in Swift 3:
let users = [Usr(1), Usr(8), Usr(5)]
let maxAge = users.map { $0.age }.max()
print(maxAge ?? "No users") // Optional(8)
Comments
let array1 = [75,37,45,80,75,24,65,97,60,83]
var smallvalue = 0
for countindex in 0..<array1.count {
let index1 = array1[countindex]
if countindex == 0 {
let index2 = array1[countindex + 1]
if index1 < index2 {
smallvalue = index1
} else {
smallvalue = index2
}
} else {
if smallvalue > index1 {
smallvalue = index1
}
}
}
print(smallvalue) //print 24
var studentsAndScores = ["Amy": Int(readLine()!)!, "James": Int(readLine()!)!, "Helen": Int(readLine()!)!]
func highestScore(scores: [String: Int]) {
let a = studentsAndScores["Amy"]!
let b = studentsAndScores["James"]!
let c = studentsAndScores["Helen"]!
var temp = 0
if a > temp {
temp = a
}
if b > temp {
temp = b
}
if c > temp {
temp = c
}
print(temp)
}
highestScore(scores: studentsAndScores)
1 Comment
Itération 122442
Avoid code only answer and provide an explanation.
[yourArray valueForKeyPath:@"@max.age"];developer.apple.com/library/ios/documentation/Cocoa/Conceptual/…