Reading from a text file in swift and dealing with white space - arrays

Question

I'm learning Swift and I'd just like to know the best way to go about reading in a text file, breaking it up into lines and then taking each word on each line and turn the words into strings that can be loaded into class initialisers.
For example, if I have this text file:
**This is just a random text file, and the text on this line
and this line is not needed**
birth year birth month birth day favourite colour
1990 11 12 red
1995 2 4 pink
1992 5 3 orange
1987 3 19 blue
I want to take the birth year, birth month, birth day and favourite colour from each line and then load it into a class like this:
Person(birthYear: 1990, birthMonth: 11, birthDay: 12, favouriteColour: red)
The text file that I want to read in might have an uneven amount of spaces so the output will look like this (for the given text file):
["**This", "is", "just", "a", "random", "text", "file,", "and", "the", "text", "on", "this", "line"]
["and", "this", "line", "is", "not", "needed**"]
["birth", "year", "", "", "", "birth", "month", "", "", "birth", "day", "", "", "", "", "favourite", "colour"]
["1990", "", "", "", "", "", "", "", "", "", "11", "", "", "", "", "", "", "", "", "", "", "", "12", "", "", "", "", "", "", "", "", "", "", "", "red"]
["1995", "", "", "", "", "", "", "", "", "", "", "2", "", "", "", "", "", "", "", "", "", "", "", "", "4", "", "", "", "", "", "", "", "", "", "", "", "pink", ""]
["1992", "", "", "", "", "", "", "", "", "", "", "5", "", "", "", "", "", "", "", "", "", "", "", "", "3", "", "", "", "", "", "", "", "", "", "", "", "orange"]
["1987", "", "", "", "", "", "", "", "", "", "", "3", "", "", "", "", "", "", "", "", "", "", "", "19", "", "", "", "", "", "", "", "", "", "", "", "blue"]
Here is my code so far:
let path = "path to my file"
if let contents = try? String(contentsOfFile: path) {
// breaking the text file up into lines
let lines = contents.components(separatedBy: "\n")
// breaking the lines up into wordsw
for line in lines {
let elements = line.components(separatedBy: " ")
print(elements)
}
}
I'm just wondering what the best way to deal with white space in these cases would be. Thank you in advance for your replies.

Answer 1

You can use a simple solution to clean all Tabs and Double spaces. Try use this piece of code.
func cleanTabsAndSpace(in text:String) -> String {
var newText = text
newText = newText.filter{ $0 != "\t" }.reduce(""){ str, char in
if let lastChar = str.last, lastChar == " " && lastChar == char {
return str
}
return str + String(char)
}
return newText.trimmingCharacters(in: .whitespacesAndNewlines)
}
After create this function you can call it inside your function
if let contents = try? String(contentsOfFile: path) {
// Clean undesired chars
let cleanContent = cleanTabsAndSpace(in: contents)
// breaking the text file up into lines
let lines = cleanContent.components(separatedBy: "\n")
// breaking the lines up into wordsw
for line in lines {
let elements = line.components(separatedBy: " ")
print(elements)
}
}
With this you will have all your content separated as you wish. Now you have just to follow as you want, parsing the content as you want and create your objects.
I'm just considering this structure you described in your question.
Good luck friend and Feel free to contact me if you need something more.

Answer 2

There is a split(separator:maxSplits:omittingEmptySubsequences:)
method which allows to split a String
into an array of SubStrings.
In contrast to components(separatedBy:) this method (by default)
omits empty substrings caused by consecutive separator characters.
Example:
let line = "1990 11 12 red"
let elements = line.split(separator: " ")
print(elements) // ["1990", "11", "12", "red"]
Here element has the type [SubString], i.e. the substrings reference
the original character storage in line, without duplicating it.
If you need "real" strings, then change it to
let elements = line.split(separator: " ").map(String.init)
Applied to your case:
if let contents = try? String(contentsOfFile: path) {
let lines = contents.components(separatedBy: "\n")
for line in lines {
let elements = line.split(separator: " ")
print(elements)
}
}