如何在Swift中将绘图保存到tableview？

Question

Im making a simple drawing app and Im trying to get my drawing saved in a tableview when I press the save button. Im using an UIImageView to allow the users to draw on. Is this the correct way to save an image with NSUserdefaults and how would I save it in a table view? Thank you! This is the code Im putting in my save button:

@IBAction func saveButton(sender: AnyObject) {


self.navigationController?.popToRootViewControllerAnimated(true)
self.navigationController?.setNavigationBarHidden(false, animated: true)
self.navigationController?.toolbarHidden = false


UIGraphicsBeginImageContextWithOptions(view.bounds.size, false, 0.0)
view.drawViewHierarchyInRect(view.bounds, afterScreenUpdates: true)
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()



let data = UIImagePNGRepresentation(image)
let userDefaults = NSUserDefaults.standardUserDefaults()
userDefaults.setObject(data, forKey: "drawing")
userDefaults.synchronize()



}    

Answer 1

Although allowed, we should not use use NSUserDefaults to save heavy data like images. You can easily use file system for that purpose like this:

Saving the image:

UIGraphicsBeginImageContextWithOptions(view.bounds.size, false, 0.0)
view.drawViewHierarchyInRect(view.bounds, afterScreenUpdates: true)
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
let data = UIImagePNGRepresentation(image)

let documentsURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)[0]
let fileURL = documentsURL.URLByAppendingPathComponent("myImage.png").path!

data?.writeToFile(fileURL, atomically: true)

And then later on fetch the image and put it on your UITableView

Fetching the image:

let documentsURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)[0]
let fileURL = documentsURL.URLByAppendingPathComponent("myImage.png").path!
let image = UIImage(contentsOfFile: fileURL)

Answer 2

You need to create a UITableViewController and populate it with your images from user defaults.

You would need to save the images in an array and fetch that array in the UITableViewController. Then in the UITableViewDataSource functions you would return a cell populated with the corresponding drawing from NSUserDefaults.

You need to implement:

public func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int

public func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell

You probably should look into saving the image in core data or the file system instead. It's more suited for this kind of storage.