Compiling Swift source files hangs on large array reduce-combine + expressions - arrays

Question

In my tests I'm used to write Strings in arrays in different lines like
let jsonString = ["{"
,"\"url\": \"http://localhost:8090/rest/api/3\","
, "\"id\": \"3\","
, "\"description\": \"A test that needs to be done.\","
, "\"name\": \"Test\","
, "\"subtest\": false,"
, "\"avatar\": 1"
,"}"].reduce("", combine: +)
That works fine, still my array get 145 lines for a large test json string.
With 145 lines (or maybe less, didn't tried it line by line) the build task hangs while "Compiling Swift source files".
First, that is a bit crazy. 30 lines are ok, 145 not? What?
Second, what is a better solution to write a String in multiple lines in Swift? - I don't want to load a json and parse it from an external file.

Answer 1

This is probably because of type inference.
Try giving an explicit [String] type to an array variable to help the compiler figure it out, then apply reduce to the variable.
let arrayOfStrings: [String] = ["{"
,"\"url\": \"http://localhost:8090/rest/api/3\","
, "\"id\": \"3\","
, "\"description\": \"A test that needs to be done.\","
, "\"name\": \"Test\","
, "\"subtest\": false,"
, "\"avatar\": 1"
,"}"] // etc
let jsonString = arrayOfStrings.reduce("", combine: +)
Anyway, to create JSON you should make a dictionary then serialize it with NSJSONSerialization, this is less error prone:
Swift 2
do {
// Create a dictionary.
let dict = ["url": "http://localhost:8090/rest/api/3", "id": "3"] // etc
// Encode it to JSON data.
let jsonData = try NSJSONSerialization.dataWithJSONObject(dict, options: [])
// Get the object back.
if let jsonObject = try NSJSONSerialization.JSONObjectWithData(jsonData, options: []) as? [String:String] {
print(jsonObject)
}
// Get it as a String.
if let jsonString = String(data: jsonData, encoding: NSUTF8StringEncoding) {
print(jsonString)
}
} catch let error as NSError {
print(error)
}
Swift 3
do {
// Create a dictionary.
let dict = ["url": "http://localhost:8090/rest/api/3", "id": "3"] // etc
// Encode it to JSON data.
let jsonData = try JSONSerialization.data(withJSONObject: dict, options: [])
// Get the object back.
if let jsonObject = try JSONSerialization.jsonObject(with: jsonData, options: []) as? [String:String] {
print(jsonObject)
}
// Get it as a String.
if let jsonString = String(data: jsonData, encoding: String.Encoding.utf8) {
print(jsonString)
}
} catch let error as NSError {
print(error)
}