iOS 多次保存带进度条的解析对象

我发现这个非常有趣的方法（解析：是否可以跟踪 PFObject 上传的进度 https://stackoverflow.com/questions/24010913/parse-is-it-possible-to-follow-progress-of-pfobject-upload）并且我尝试在快速扩展中转换 Objective-C 类别。但我对值类型感到过度紧张unsigned long.
请查看以下代码 - 它抛出异常（行：let progress:Int32 = Int32(100*count/numberOfCyclesRequired)): 致命错误：浮点值无法转换为 Int32，因为它是无穷大或 NaN。我也不确定如何处理__blockswift 中的前缀表明计数变化也会发生在块外。

extension PFObject {

class func saveAllInBackground(objects: [AnyObject]!, chunkSize:Int, block: PFBooleanResultBlock!, progressBlock:PFProgressBlock) {

    let numberOfCyclesRequired:Double = Double(objects.count / chunkSize)
    var count:Double = 0
    PFObject.saveAllInBackground(objects, chunkSize: chunkSize, block: block) { (trig:Bool) -> Void in
        count++
        let progress:Int32 = Int32(100*count/numberOfCyclesRequired)
        progressBlock(progress)
    }
}

class func saveAllInBackground(objects: [AnyObject]!, chunkSize:Int, block: PFBooleanResultBlock!, trigger:(Bool) -> Void) {
    let range = NSMakeRange(0, objects.count <= chunkSize ? objects.count:chunkSize)
    var saveArray:NSArray = (objects as NSArray).subarrayWithRange(range)
    var nextArray:NSArray = []
    if range.length < objects.count {
        nextArray = (objects as NSArray).subarrayWithRange(NSMakeRange(range.length, objects.count-range.length))
    }
    PFObject.saveAllInBackground(saveArray) { (succeeded:Bool, error: NSError!) -> Void in
        if (error == nil && succeeded && nextArray.count != 0) {
            trigger(true)
            PFObject.saveAllInBackground(nextArray, chunkSize: chunkSize, block: block, trigger: trigger)
        } else {
            trigger(true)
            block(succeeded,error)
        }
    }
}

}

提前感谢您的帮助。