在Swift中向字符串追加一个字符串数组

Question

I have an array of strings for one variable, and a string as another variable. I'd like to append all of the strings in the collection to the single string.

So for example I have:

 var s = String()

   //have the CSV writer create all the columns needed as an array of strings
   let arrayOfStrings: [String] = csvReport.map{GenerateRow($0)}

// now that we have all the strings, append each one 
        arrayOfStrings.map(s.stringByAppendingString({$0}))

the line above fails. I've tried every combination I can think of, but at the end of the day, I can't get it unless I just create a for loop to iterate through the entire collection, arrayOfStrings, and add it one by one. I feel like I can achieve this the same way using map or some other function.

Any help?

Thanks!

Answer 1

You can use joinWithSeparator :

let stringArray = ["Hello", "World"]
let sentence = stringArray.joined(separator: " ")  // "Hello World"

Answer 2

You could convert your array to string using joinWithSeparator(String) here is an example

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

source: [ How do I convert a Swift Array to a String? ]

Answer 3

There are at least two options here. The most semantic choice is likely joinWithSeparator on the [String] object. This concatenates every string in the array, placing the separator provided as a parameter between each string.

 let result = ["a", "b", "c", "d"].joinWithSeparator("")

An alternative is to use a functional reduce and the + function operator which concatenates strings. This may be preferred if you want to do additional logic as part of the combine. Both example code produce the same result.

 let result = ["a", "b", "c", "d"].reduce("", combine: +)

It's also worth noting the second options is transferrable to any type that can be added, whereas the first only works with a sequence of strings, as it is defined on a protocol extension of SequenceType where Generator.Element == String .