ios - 从 Parse sdk 检索 Swift 图像 - 崩溃

Question

我正在使用 Swift 使用以下代码从 Parse 检索图像集。

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


}

我的解析类详细信息

类(class)名称 - 图片

当我运行这个函数时，它崩溃了，控制台中没有任何消息。

注意:我可以在回调中获取 PFFile 对象的集合。

我换了 "thumbNail.getDataInBackgroundWithBlock({...." block 与同步函数调用 thumbNail.getData() 类似 “var imageData=thumbNail.getData() var image = UIImage(data:imageData)"

然后错误说

Warning: A long-running operation is being executed on the main thread. Break on warnBlockingOperationOnMainThread() to debug.

所以，我恢复到 thumbNail.getDataInBackGroundWithBloack({... 但是现在，控制台中没有错误显示，就像以前一样。我的方法有什么问题请告诉我。任何帮助将不胜感激...!

Answer 1

我设法重现了错误，这似乎是 PFObject 上的某种内存泄漏/僵尸。我不确定到底是为什么，但是按照以下方式重构您的代码可以消除我的错误:

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
}

编辑:顺便说一句，这也有效:

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


}

这表明错误是由于以下行造成的:

for object : PFObject! in objects as [PFObject] {

重写该行如下:

for object : PFObject in objects as [PFObject] {

同时删除错误。所以这个错误的原因似乎是你告诉程序打开一些不是可选的东西。