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i have an array which contains strings i.e Array

i tried to concatenate string, but i got an error as "String is not identical to UInt8"

var titleString:String! = "" for title in array { titleString += "\(title)" }
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    Why did you make that string optional? Commented Oct 27, 2014 at 8:11
  • By mistake. I edited my question Commented Oct 27, 2014 at 8:18
  • It didn't work because you declared the titleAnswer as implicitly unwrapped optional. Now that you've turned into a non optional, it should work - see my answer below (there's also a better way to concatenate) Commented Oct 27, 2014 at 8:21
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    Does your code (after the edit) actually produce that error message? Otherwise your question is unclear. Commented Oct 27, 2014 at 8:25
  • @MartinR: You're right.i am getting empty string after concatenate operation. Commented Oct 27, 2014 at 8:37

2 Answers 2

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To concatenate all elements of a string array, you can use the reduce method:

var string = ["this", "is", "a", "string"] let res = string.reduce("") { $0 + $1 }

The first parameter is the initial string, which is empty, and the second is a closure, which is executed for each element in the array. The closure receives 2 parameters: the value returned at the previous step (or the initial value, if it's the 1st element), and the current element value.

More info here

Addendum I forgot to explicitly answer to your question: the concatenation doesn't work because you declared the titleString as optional - just turn into a non optional variable and it will work. If you still want to use the optional, then use forced unwrapping when doing the assignment:

titleString! += "\(title)"

Addendum 2 As suggested by @MartinR, there's another simpler way to concatenate:

join("", string)
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5 Comments

Thanks for explanation. It works. I am just started learning swift. I am not familiar with Optional Chaining. Will dig into it.
one more question. I want to display array of strings in multi line in a cell. How can i do that. can you guide me?
That's more complicated than just concatenating an array of strings. I suggest to search for a good tutorial, raywenderlich.com and appcoda.com have great ones
i thought of appending "\n" to string and display it in uilabel.
@Antonio, your solution be further reduced to: let res = string.reduce("", +)
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In Swift 3, this is how you join elements of a String array:

 ["this", "is", "a", "string"].joined(separator: "")

Although, joined(separator:) is really geared for actually putting a separator between the strings. Reduce is still more concise:

 ["this", "is", "a", "string"].reduce("", +)
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As of Swift 5, joined() - with no parameters achieves the same thing

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