在 Swift 中如何从数组中移除给定值的元素

我想从一个包含 x、 y 和 z 元素的数组中移除所有值 x 的元素

let arr = ['a', 'b', 'c', 'b']

如何从 arr 中删除值‘ b’的所有元素？

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最佳答案

A filter:

 let farray = arr.filter {$0 != "b"}
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A general approach is to exploit first class procedures. (However, this approach is much more powerful than what is required for your question.) To illustrate, say you want to avoid "Justin" repeatedly in many collections.

let avoidJustin = notEqualTester ("Justin")


let arrayOfUsers = // ...


arrayOfUsers.filter (avoidJustin)


let arrayOfFriends = // ...


arrayOfFriends.filter (avoidJustin)

With this, you avoid repeatedly creating a closure each time you want to avoid Justin. Here is notEqualTester which, given a that, returns a function of this that returns this != that.

func notEqualTester<T: Equatable> (that:T) -> ((this:T) -> Bool) {
return { (this:T) -> Bool in return this != that }
}

The returned closure for this captures the value for that - which can be useful when that is no longer available.

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var array : [String]
array = ["one","two","one"]


let itemToRemove = "one"


while array.contains(itemToRemove) {
if let itemToRemoveIndex = array.index(of: itemToRemove) {
array.remove(at: itemToRemoveIndex)
}
}


print(array)

Works on Swift 3.0.

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In Swift 3 I simply do:

arr = arr.filter { $0 != "a" }

.filter, .sort and .map are great for saving time and solve lots of problems with little code.

This article has good examples and explain the differences and how they work: https://useyourloaf.com/blog/swift-guide-to-map-filter-reduce/

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EDITED according to comments:

I like this approach: 

var arr = ["a", "b", "c", "b"]


while let idx = arr.index(of:"b") {
arr.remove(at: idx)
}

Original answer (before editing):

let arr = ['a', 'b', 'c', 'b']


if let idx = arr.index(of:"b") {
arr.remove(at: idx)
}
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If you need to modify initial array, you can use the function removeAll(where:) that is available in Swift 4.2/Xcode 10:

var arr = ["a", "b", "c", "b"]
arr.removeAll(where: { $0 == "b" })
print(arr) // output is ["a", "c"]

However, if you are using Xcode 9 you can find this function in Xcode9to10Preparation (this library provides implementations of some new functions from Xcode 10).

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If you have more than one element to remove, thanks to first answer.

 var mainArray = ["a", "b", "qw", "qe"]
let thingsToRemoveArray = ["qw", "b"]




for k in thingsToRemoveArray {
mainArray =  mainArray.filter {$0 != k}
}
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If you only have one element of that value, this would probably be the easiest.

arr.remove(at: arr.index(of: ‘b’))

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