如何在Swift中阅读Plist？

Question

I want read a NSArray form plist , and the code :

func loadPlistArray() -> [Any] {

    var path: String? = Bundle.main.path(forResource:"MyCenter", ofType: "plist")

    if let arry = NSArray(contentsOfFile: path!) {
        return arry as! NSArray
    }else{
        return nil;
    }

}

but always got errors below:

And After I got the data from plist, I fount that I can't see the Details of Dictionary :

And here is my plist:

should I add a generic in the array by var plistArray : [[String:Any]]?

Answer 1

The errors messages you are getting tell you what is wrong with your method, this is how I would write the function:

func loadPlistArray() -> [Any] { // 1
    guard
        let url = Bundle.main.url(forResource: "MyCenter", withExtension: "plist"), // 2
        let list = NSArray(contentsOf: url) as? [Any] // 3
        else { return [] } // 4

    return list
}

And some commentary:

1. You are declaring the method to return an Array of Any items, but your method tries to return an NSArray .
2. It is recommended to use the URL based methods for accessing files, rather then the string based paths.
3. You have to use the Array methods to read the plist, but you can cast it to [Any] . However, if you know the type of items you have in the plist, I recommend that you return a properly type array from this method eg [String] , [Int] etc.
4. You don't need to return an optional if the file can't be read. Depending on how you want to handle the error you could either return an empty array (as I've shown here) or convert your function into a throwing one so that if you can't read the file an error is thrown and can be handled by the calling code.

Answer 2

Your method signature clearly states that it returns an [Any] (ie, Swift native Array containing elements of any type whatsoever), while you try to cast the return value into NSArray (even though it already is by virtue of intialization: NSArray(contentsOfFile:) ).

Change it to:

return arry as? [Any] 
// (will return nil if the cast fails - not a problem if you
//  also apply the fix mentioned below...)

The other path tries to return nil ; for that to be acceptable, your signature needs to be defined as returning an optional :

func loadPlistArray() -> [Any]  // WRONG

func loadPlistArray() -> [Any]? // RIGHT

EDIT: If your app is structured in such a way that you can't afford to return nil from your method, you can instead return an empty array on failure:

else {
    return [] // Empty array
}

(use [:] for empty dictionary)

---

Also, try to avoid using ! whenever possible, and switch to ? instead, unless you are 100% sure that whatever it is you are forcing will not fail and cause a runtime error (crash).

Answer 3

I am using something like this in my project.

  if let fileUrl = Bundle.main.url(forResource: "new", withExtension: "plist"),
     let myDict = NSDictionary(contentsOf: fileUrl) as? [String:Any] {
            print(myDict)
        }

I have another plist for color which have array as a root.

        if let fileUrl = Bundle.main.url(forResource: "color", withExtension: "plist"),
        let data = try? Data(contentsOf: fileUrl) {
        if let result = try? PropertyListSerialization.propertyList(from: data, options: [], format: nil) as? [Any] {
            print(result)
        }
    }

Answer 4

     return (arry ) as! [Any]

您不能在Any类型上返回NSArray