如何使用一行代码在Swift 2.0中读取文本文件

Question

I'm trying to read the contents of a file.

In Python, it would be a one liner:

seq_file = open('/some/local/file-path/on/computer.txt','r').read()
print seq_file

How can you write a one-liner in Swift to do the same thing?

My swift code to open a file (only works in terminal not in Playground):

let seq_path = "/some/local/file-path/on/computer.txt"
let file_manager = NSFileManager.defaultManager()
let data: NSData = file_manager.contentsAtPath(seq_path)!
let seq_file = NSString(data: data, encoding: NSUTF8StringEncoding)
print(seq_file)

I'm not sure why reading is so much more complicated in Swift. If someone would like to explain that would be extremely helpful.
I've read about the advantages of Swift...If it's so new and powerful, why would they make such a simple task so complicated?

Background (if anyone is interested): Undergrad in Biology, started learning Python in 2012 as my first programming language. Use it to analyze biological data to this day. Now I'm a graduate student and I've been getting a lot more interested in Computer Science over the years. I would like to start writing programs for OSX and iOS and I thought a good way to learn the language was rewrite all my algorithms in Swift.

Answer 1

Dunno, I suppose language designers have their priorities. Charitably, the swift code could lose a line and still read well:

let file_manager = NSFileManager.defaultManager()
let data: NSData = file_manager.contentsAtPath("/some/local/file-path/on/computer.txt")!
let seq_file = NSString(data: data, encoding: NSUTF8StringEncoding)
print(seq_file)

This is more or less what it took to read a file with java 1.4:

try
{
    String line;
    File file = new File(("manifest.mf");
    BufferedReader inFile = new BufferedReader(new FileReader(file));
    while((line = inFile.readLine()) != null)
    {
            System.out.println(line)
    }
    inFile.close();
}
catch (IOException e)
{
    System.out.println("problem with file");
}

In java 8, you can do something like this:

    Files.lines(Paths.get("manifest.mf")).forEach(System.out::println);

Things change. Swift is at 1.2. It does seem a bit old fashioned though.

Answer 2

I've read about the advantages of Swift...If it's so new and powerful, why would they make such a simple task so complicated?

Well, in Swift you can do this:

let string = try? NSString(contentsOfFile: "name.txt", encoding: NSASCIIStringEncoding)
print(string)

The question is if you really want to, because the longer versions give you more flexibility and better error handling...