我知道如何通过编程来做到这一点,但我相信有一种内置的方式……

我使用过的每种语言都有某种对象集合的默认文本表示,当您试图将Array与字符串连接起来或将其传递给print()函数等时,它会吐出这些文本表示。苹果的Swift语言是否有一种内置的方式,可以轻松地将数组转换为字符串,或者我们总是必须显式地对数组进行字符串化?


当前回答

当你也有struct数组时,你可以使用joined()来获得单个String。

struct Person{
    let name:String
    let contact:String
}

使用map() & joined()可以轻松生成字符串

PersonList.map({"\($0.name) - \($0.contact)"}).joined(separator: " | ")

输出:

Jhon - 123 | Mark - 456 | Ben - 789  

其他回答

斯威夫特3

["I Love","Swift"].joined(separator:" ") // previously joinWithSeparator(" ")

如果你想在数组中丢弃空字符串。

["Jet", "Fire"].filter { !$0.isEmpty }.joined(separator: "-")

如果你也想过滤nil值:

["Jet", nil, "", "Fire"].flatMap { $0 }.filter { !$0.isEmpty }.joined(separator: "-")

对于任何元素类型

extension Array {

    func joined(glue:()->Element)->[Element]{
        var result:[Element] = [];
        result.reserveCapacity(count * 2);
        let last = count - 1;
        for (ix,item) in enumerated() {
            result.append(item);
            guard ix < last else{ continue }
            result.append(glue());
        }
        return result;
    }
}

修改一个可选/非可选字符串数组

//Array of optional Strings
let array : [String?] = ["1",nil,"2","3","4"]

//Separator String
let separator = ","

//flatMap skips the nil values and then joined combines the non nil elements with the separator
let joinedString = array.flatMap{ $0 }.joined(separator: separator)


//Use Compact map in case of **Swift 4**
    let joinedString = array.compactMap{ $0 }.joined(separator: separator

print(joinedString)

这里是flatMap, compactMap跳过数组中的nil值,并附加其他值以给出一个连接字符串。

Swift 2.0 Xcode 7.0 beta 6以上使用joinWithSeparator()代替join():

var array = ["1", "2", "3"]
let stringRepresentation = array.joinWithSeparator("-") // "1-2-3"

joinWithSeparator被定义为SequenceType的扩展

extension SequenceType where Generator.Element == String {
    /// Interpose the `separator` between elements of `self`, then concatenate
    /// the result.  For example:
    ///
    ///     ["foo", "bar", "baz"].joinWithSeparator("-|-") // "foo-|-bar-|-baz"
    @warn_unused_result
    public func joinWithSeparator(separator: String) -> String
}