I'm writing a function to query the class Photos with a given Object Id in order to download a photo and set it to the UIImageView "background." I've narrowed the issue down to "for object in objects!" which I've commented in the code below. This seems like standard practice for casting, but the code won't run past this point. It compiles and no errors are thrown, but it fails to print anything past the "for" line, much less set the background.
// set new background image
func imageSet(objId: String) {
var query : PFQuery = PFQuery(className: "Photos")
query.whereKey("objId", equalTo:objId)
query.findObjectsInBackgroundWithBlock {
(objects:[AnyObject]?, error:NSError?) -> Void in
if error == nil {
println("First query")
// last working line
for object in objects! {
println("Won't print here")
// won't pass this point
let userImageFile = object["image"] as! PFFile
userImageFile.getDataInBackgroundWithBlock {
(imageData: NSData?, error:NSError?) -> Void in
if error == nil {
println("Or here")
self.background.image = UIImage(data:imageData!)
}
}
}
}
else {
println("\(error)")
}
}
}
Any tips are greatly appreciated! Thanks!
Related
Below is an example of how i would typically retrieve images from my Parse.com. I have now run into the situation where i would like to retrieve 20+ images from Parse but i am looking for a more efficient way to do so. Please can someone explain how to implement this in code and how i should store the 20+ PFFiles in Parse?
func loadData(){
let findDataParse = PFQuery(className: "JobListing")
findDataParse.findObjectsInBackgroundWithBlock{
(objects: [PFObject]?, error: NSError?) -> Void in
if (error == nil) {
for object in objects! {
let userImageFile = object["ImageOne"] as! PFFile
let userImageFile1 = object["ImageTwo"] as! PFFile
let userImageFile2 = object["ImageThree"] as! PFFile
userImageFile.getDataInBackgroundWithBlock {
(imageData: NSData?, error: NSError?) -> Void in
let listingImage1 = UIImage(data:imageData!)
userImageFile1.getDataInBackgroundWithBlock {
(imageData1: NSData?, error1: NSError?) -> Void in
let listingImage2 = UIImage(data:imageData1!)
userImageFile2.getDataInBackgroundWithBlock {
(imageData2: NSData?, error1: NSError?) -> Void in
let listingImage3 = UIImage(data:imageData2!)
self.flyerImageLarge1.image = listingImage1
self.flyerImageLarge2.image = listingImage2
self.flyerImageLarge3.image = listingImage3
}}}}}}}
You can use ParseUI for cleaner and more efficient code.
To do so, add the ParseUI framework.
Then, click the image and change the "class" to PFImageView.
You can see this here.
Once you do that, you can easily set the PFImageView's image:
if let myServerImage = object.valueForKey("imageFromUser") as? PFFile {
self.myImage.file = myServerImage
self.myImage.loadInBackground()
}
Where myServerImage is the image you are retrieving from the Parse server and myImage is the image in your storyboard.
In your case it will be something like this:
func loadData(){
let findDataParse = PFQuery(className: "JobListing")
findDataParse.findObjectsInBackgroundWithBlock{
(objects: [PFObject]?, error: NSError?) -> Void in
if (error == nil) {
if let myServerImage = object.valueForKey("ImageOne") as? PFFile {
self.flyerImageLarge1.file = myServerImage
self.flyerImageLarge1.loadInBackground()
}
if let myServerImage = object.valueForKey("ImageTwo") as? PFFile {
self.flyerImageLarge2.file = myServerImage
self.flyerImageLarge2.loadInBackground()
}
if let myServerImage = object.valueForKey("ImageThree") as? PFFile {
self.flyerImageLarge3.file = myServerImage
self.flyerImageLarge3.loadInBackground()
}
}
}
I recommend adding the if let statement so that you don't get an error when an image doesn't exist.
Please forgive me if what I am saying is obvious or already considered. I'm not completely familiar with what you are doing, but it looks applicable.
Assuming you are not using it already, you will need to use a recursive function. Basically, a function that calls itself until the end condition.
I'm not familiar with your code so I'll demonstrate with a simple example in JavaScript:
/* A "public" function that your program will call */
function getStuff(total)
{
//quick positive check
if (total > 0)
{
//start and pass in an empty array
return _getStuffRecursion(total, []);
}
else
{
//total is not positive, return empty array
return [];
}
}
/* A "private" function that will do the recursion */
function _getStuffRecursion(total, resultsArray)
{
//do work this is where you would call your function that does the work.
var someResource = Math.random();
//add work to the array collected so far
resultsArray.push(someResource);
//change count
var newTotal = total - 1;
//check condition
if (newTotal > 0)
{
//recursive condition, go to the next level down and pass in what is collected so far
return _getStuffRecursion(newTotal, resultsArray)
}
else
{
//end condition met, just return the array with everything collected from the upper levels
return resultsArray;
}
}
/* Start */
//get started by calling the "public" function
var results = getStuff(20);
//print it to console
console.log(results);
If this solution works, I'm sure you can adapt it to Parse.
Noob question here and I know my code below is very wrong but it works in that it retrieves the 3 images I need. However, I'd like to know a better way to retrieve multiple images from Parse.
Any help would be greatly appreciated!
func retrieveImage() {
var query = PFQuery(className: "Items")
query.orderByDescending("createdAt")
query.findObjectsInBackgroundWithBlock { (objects: [AnyObject]?, error: NSError?) -> Void in
if error == nil {
let imageObjects = objects as! [PFObject]
for (index, object) in enumerate(imageObjects) {
let thumbnail1 = object["image1"] as! PFFile
let thumbnail2 = object["image2"] as! PFFile
let thumbnail3 = object["image3"] as! PFFile
thumbnail1.getDataInBackgroundWithBlock{(imageData: NSData?, error: NSError?) -> Void in
if error == nil {
if let image = UIImage(data: imageData!) {
self.itemImages[index] = image
}
}
thumbnail2.getDataInBackgroundWithBlock{(imageData: NSData?, error: NSError?) -> Void in
if error == nil {
if let image = UIImage(data: imageData!) {
self.itemImages2[index] = image
}
}
}
thumbnail3.getDataInBackgroundWithBlock{(imageData: NSData?, error: NSError?) -> Void in
if error == nil {
if let image = UIImage(data: imageData!) {
self.itemImages3[index] = image
}
}
}
}
}
}
}
}
First the idea... we want to do an arbitrarily long list of asynch tasks, collect their results, and be notified on completion or error. We do this by parameterizing the task (in this case, the PFFiles whose contents are to be fetched are the parameters), and we use those parameters as a "to-do list".
A recursive function does the work, picking off the first item in the list, doing the asynch task, and then calling itself with the remainder of the list. An empty to-do list means we're done.
I've tried to translate the answer I referred to here into swift (literally learning the language line by line)....
func load(pfFiles: Array<PFFile>, var filling: Dictionary<PFFile, UIImage>, completion: (success: Bool) -> Void) {
completion(success: true)
var count = pfFiles.count
if (count == 0) {
return completion(success: true)
}
var file = pfFiles[0]
var remainder = Array(pfFiles[1..<count])
file.getDataInBackgroundWithBlock{(imageData: NSData?, error: NSError?) -> Void in
if error == nil {
if let image = UIImage(data: imageData!) {
filling[file.name] = image
self.load(remainder, filling: filling, completion: completion)
}
} else {
completion(success: false)
}
}
}
Given this is my first attempt, I'll be a little shocked and delighted if it works, but the algorithm is sound, and the swift compiles and appears to match the idea I outlined. Here's how to call it...
var pfFiles: Array<PFFile>
for (index, object) in enumerate(imageObjects) {
pfFiles.append(object["image1"])
pfFiles.append(object["image2"])
pfFiles.append(object["image3"])
}
var filling: Dictionary<String, UIImage>
// call the function here
// in the completion assign filling to property
// anytime after, when you have a PFFile like someObject["image2"]
// you use its name to look it up the UIImage in the results dictionary
Let me know if that last bit is clear enough. As you can see, I ran out of steam on my swift translation and resorted to pseudo code.
I believe you can just do self.itemImages[index] = thumbnail1.getData()!
If it crashs, do : query.includeKey("image1")
NOTE:
If you afraid to block the main queue, open a new thread to do such thing
Hi I have a PFQuery where I am retrieving map images and I need to sort them so that i can retrieve the correct image in my code. This is currently my code:
func retrieveImages() {
self.imageArray = [UIImage]()
var query = PFQuery(className:"Maps")
query.orderByDescending("createdAt")
query.findObjectsInBackgroundWithBlock {
(objects: [AnyObject]?, error: NSError?) -> Void in
if error == nil {
if let objects = objects as? [PFObject] {
for object in objects {
self.objectNames.append(object["Name"]!)
let userImageFile = object["imageFile"] as! PFFile
userImageFile.getDataInBackgroundWithBlock {
(imageData: NSData?, error: NSError?) -> Void in
if error == nil {
if imageData != nil {
let imageData = imageData
var image = UIImage(data:imageData!)
if image != nil {
self.imageArray.append(image!)
}
}
}
}
}
}
}
}
}
I tried to sort the query by using the orderByDescending function but when i run the code only the names of the objects are sorted and the images themselves are not. There also seems to be no pattern in how the images are sorted because each time I run this code the order of the images are different. Any advice or insight would be appreciated.
I have a PFQueryTableViewController populated by comments from different users. Each user has a profile picture stored on the Parse database. After loading each comment into a cell, I query the PFUser class to retrieve the profile picture of the user who posted the comment and add it to the cell. I also use PFCachePolicy to cache the profile picture to the device's memory so that displaying new cells with new profile pictures is a smoother transition.
However this is not the case. When a user posts a new comment and a new cell is added, the profile pictures shuffle around and takes about two seconds or so to update with the right image (probably because the table is re-queried and updated). I am trying to achieve something similar to iMessage or WhatsApp where the profile picture remained 'fixed' in the cell.
I am not sure what the problem is or if there is a better way to do this?
// get objectId of the user who posted a comment
let senderId = object?["Users"]!.objectId as String!
// query PFUser class using senderId to retrieve profile picture
var senderImage:PFQuery = PFUser.query()!
senderImage.cachePolicy = PFCachePolicy.CacheThenNetwork
senderImage.getObjectInBackgroundWithId(senderId){
(sender: PFObject?, error: NSError?) -> Void in
if error == nil && sender?.objectForKey("profilePicture") != nil {
let thumbnail = sender?.objectForKey("profilePicture") as? PFFile
thumbnail?.getDataInBackgroundWithBlock({
(imageData: NSData?, error: NSError?) -> Void in
if error == nil {
imageView.image = UIImage(data:imageData!)
} else {
println(error)
}
})
}
}
That's because you're not waiting until the images are finished loading when you update the UIImageView. Try Using this code:
var query = PFQuery(className:"Users")
query.findObjectsInBackgroundWithBlock {
(objects: [AnyObject]?, error: NSError?) -> Void in
if error == nil {
// The find succeeded.
self.scored = objects!.count
// Do something with the found objects
if let objects = objects as? [PFObject] {
for object in objects {
let userImageFile = object["Image"] as! PFFile
userImageFile.getDataInBackgroundWithBlock {
(imageData: NSData?, error: NSError?) -> Void in
if error == nil {
if let imageData = imageData {
let image = UIImage(data:imageData)
self.imageArray.append(image!)
}
}
dispatch_async(dispatch_get_main_queue()) {
//don't reload image view here!
}
}
}
}
} else {
// Log details of the failure
print("Error: \(error!) \(error!.userInfo)")
}
dispatch_async(dispatch_get_main_queue()) {
//wait until here to reload the image view
if self.imageArray.isEmpty == false {
//image array is not empty
self.ImageView.image = imageArray.first
}
else {
//no images found in parse
}
}
I'm retrieving set of images from Parse, using the following code using Swift.
var imageResources : Array<UIImage> = []
override func viewDidLoad(){
super.viewDidLoad()
self.loadImages()
}
func loadImages(){
var query = PFQuery(className: "Images")
query.orderByDescending("objectId")
query.findObjectsInBackgroundWithBlock ({(objects:[AnyObject]!, error: NSError!) in
if(error == nil){
for object : PFObject! in objects as [PFObject] {
var thumbNail = PFFile()
thumbNail = object["image"] as PFFile
println("thumNail \(thumbNail)")
thumbNail.getDataInBackgroundWithBlock({
(imageData: NSData!, error: NSError!) in
if (error == nil) {
let image : UIImage = UIImage(data:imageData)
//image object implementation
self.imageResources.append(image)
}
})//getDataInBackgroundWithBlock - end
}//for - end
}
else{
println("Error in retrieving \(error)")
}
})//findObjectsInBackgroundWithblock - end
}
My Parse Class detail
class name - Images
When I run this function, it's getting crashed without a message in the console.
Note: I'm able to get the collection of PFFile objects in the callback.
I've replaced
"thumbNail.getDataInBackgroundWithBlock({...." block with the synchronous function call thumbNail.getData() like
"var imageData= thumbNail.getData()
var image = UIImage(data:imageData)"
Then the error says
Warning: A long-running operation is being executed on the main thread.
Break on warnBlockingOperationOnMainThread() to debug.
So, I reverted to thumbNail.getDataInBackGroundWithBloack({...
But now, there is no error display in the console, as it happens before. Is there anything wrong in my approach please let me know.
Any help would be appreciated...!
I managed to recreate the error, which seems to be some kind of memory leak / zombie on a PFObject. I'm not sure exactly why, but refactoring your code in the following manner got rid of the error in my case:
func loadImages() {
var query = PFQuery(className: "Images")
query.orderByDescending("objectId")
query.findObjectsInBackgroundWithBlock ({(objects:[AnyObject]!, error: NSError!) in
if(error == nil){
self.getImageData(objects as [PFObject])
}
else{
println("Error in retrieving \(error)")
}
})//findObjectsInBackgroundWithblock - end
}
func getImageData(objects: [PFObject]) {
for object in objects {
let thumbNail = object["image"] as PFFile
println(thumbNail)
thumbNail.getDataInBackgroundWithBlock({
(imageData: NSData!, error: NSError!) -> Void in
if (error == nil) {
let image = UIImage(data:imageData)
//image object implementation
self.imageResources.append(image)
println(image)
}
})//getDataInBackgroundWithBlock - end
}//for - end
}
EDIT: Incidentally, this also works:
func loadImages() {
var query = PFQuery(className: "Images")
query.orderByDescending("objectId")
query.findObjectsInBackgroundWithBlock ({(objects:[AnyObject]!, error: NSError!) in
if(error == nil){
let imageObjects = objects as [PFObject]
for object in objects {
let thumbNail = object["image"] as PFFile
thumbNail.getDataInBackgroundWithBlock({
(imageData: NSData!, error: NSError!) -> Void in
if (error == nil) {
let image = UIImage(data:imageData)
//image object implementation
self.imageResources.append(image)
println(image)
}
})//getDataInBackgroundWithBlock - end
}//for - end
}
else{
println("Error in retrieving \(error)")
}
})//findObjectsInBackgroundWithblock - end
}
This would indicate that the error was due to the following line:
for object : PFObject! in objects as [PFObject] {
Rewriting that line as follows:
for object : PFObject in objects as [PFObject] {
Also removes the error. So the reason for this error seems to be that that you told the program to unwrap something that wasn't an optional.