在iOS Swift2中读取本地HTML文件

Question

I have a site folder in my app. I assemble an HTML string and load it in a webview. In the process, I'm running into an error trying to load two files.

let hpath: String = "site/header.html"
let fpath: String = "site/footer.html"
let head: String = String(contentsOfFile: hPath, encoding: NSUTF8StringEncoding, error: nil)
let foot: String = String(contentsOfFile: fPath, encoding: NSUTF8StringEncoding, error: nil)
return head + foot

Error:

Cannot invoke initializer for type 'String' with an argument list of type '(contentsOfFile: String, encoding: UInt, error: NilLiteralConvertible)'

My source is the same as examples I found. Maybe it's different now in Swift 2. Either way, what needs to change so I can read the content of these two files?

Answer 1

The error handling in Swift 2 has changed. If you need to handle the error at runtime and need the error message:

var head: String
do {
    head = try String(contentsOfFile: hPath, encoding: NSUTF8StringEncoding)
}
catch let error as NSError { fatalError(error.localizedDescription) // or do something else with the error}

If you know the file will exist at runtime (eg in the application bundle):

let foot: String = try! String(contentsOfFile: fPath, encoding: NSUTF8StringEncoding)

The above will crash if the file does not exist.

Third option:

let foot: String? = try? String(contentsOfFile: fPath, encoding: NSUTF8StringEncoding)

This won't crash if the file does not exist, but returns an optional string and no error message.

Answer 2

This is how I was able to read a couple files from a directory I added to my project. I pass a body of HTML to a method, then I wrap it with a header and footer stored in the app's file system.

func assembleHTML(var html: String) -> String {
    let fileMgr = NSFileManager.defaultManager()
    let hPath = NSBundle.mainBundle().pathForResource("site/header", ofType: "html")!
    let fPath = NSBundle.mainBundle().pathForResource("site/footer", ofType: "html")!
    var hContent: String?
    var fContent: String?
    if fileMgr.fileExistsAtPath(hPath) && fileMgr.fileExistsAtPath(fPath) {
        do {
            hContent = try String(contentsOfFile: hPath, encoding: NSUTF8StringEncoding)
            fContent = try String(contentsOfFile: fPath, encoding: NSUTF8StringEncoding)
        } catch let error as NSError {
            print("error:\(error)")
        }
    } else {
        print("not found")
    }
    html = hContent! + html + fContent!
    return html;
}