Type 'AnyObject' does not conform to protocol 'SequenceType'

Question

func loadThumbnails() {

    let paths = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true)
    let documentsDirectory:NSString = paths[0] as NSString
    var error:NSError?
    let fileManager = NSFileManager()
    let directoryContent:AnyObject = fileManager.contentsOfDirectoryAtPath(documentsDirectory, error: &error)!

    thumbnails = [QSPhotoInfo]()

    for item:AnyObject in directoryContent {
        let fileName = item as NSString
        if fileName.hasPrefix(kThumbnailImagePrefix) {
            let image = loadImageFromDocumentsDirectory(fileName)
            var photoInfo = QSPhotoInfo()
            photoInfo.thumbnail = image;
            photoInfo.thumbnailFileName = fileName
            thumbnails += photoInfo
        }
    }
}

the compile error is below:

Type 'AnyObject' does not conform to protocol 'SequenceType'

what does this menas?

who can help me ,thks a lot!!!!

Answer 1

Apple states in The Swift Programming Language :

The for-in loop performs a set of statements for each item in a range, sequence, collection, or progression.

Right now, directoryContent is just conforming to protocol AnyObject , so you can't use for loops over it. If you want to do so, you have to do something similar to the following:

for item in directoryContent as [AnyObject] {
    //Do stuff
}

Answer 2

contentsOfDirectoryAtPath returns an NSArray , whereas you are casting it to AnyObject . The solution is to cast it to either [AnyObject]? or NSArray :

let directoryContent: [AnyObject]? = fileManager.contentsOfDirectoryAtPath(documentsDirectory, error: &error)

or

let directoryContent: NSArray? = fileManager.contentsOfDirectoryAtPath(documentsDirectory, error: &error)

Then use an optional binding before the for loop:

if let directoryContent = directoryContent {
    for item:AnyObject in directoryContent {

Looking at the contentsOfDirectoryAtPath documentation, it states it always returns an array - so what said above can be reduced to unwrapping the return value to either a swift or objc array, with no need to use the optional binding:

let directoryContent: [AnyObject] = fileManager.contentsOfDirectoryAtPath(documentsDirectory, error: &error)!

or

let directoryContent: NSArray = fileManager.contentsOfDirectoryAtPath(documentsDirectory, error: &error)!