Question

我的应用程序崩溃并出现以下错误，我正在尝试复制它，但是我不能，所以有人可以提供一些有关出了什么问题的见解吗？

class ViewController: UIViewController {
 //all the usual class methods here

 @objc func getData() {
self.array = []
let predicate = NSPredicate(value: true)
let query = CKQuery(recordType: “Product”, predicate: predicate)

let queryOperation = CKQueryOperation(query: query)
queryOperation.resultsLimit = 5
queryOperation.qualityOfService = .userInitiated
queryOperation.recordFetchedBlock = { record in
    self.array.append(record)
}
queryOperation.queryCompletionBlock = { cursor, error in
    if error != nil{
      cloudkitHelper.request(error: error!, viewController: self). //this line causes the crash

    }
    else{
        if cursor != nil {
            self.askAgain(cursor!)
        }
    }
    OperationQueue.main.addOperation {
        self.tableView.reloadData()
    }
}
Database.share.publicDB.add(queryOperation)
}

func askAgain(_ cursor: CKQueryOperation.Cursor) {
let queryOperation = CKQueryOperation(cursor: cursor)
queryOperation.resultsLimit = 5

queryOperation.recordFetchedBlock = {
    record in
    self.array.append(record)
}
queryOperation.queryCompletionBlock = { cursor, error in
    if error != nil{
        cloudkitHelper.request
    }
    else{
        if cursor != nil {
            self.askAgain(cursor!)
        }
    }
    OperationQueue.main.addOperation {
        self.tableView.reloadData()
    }
}
Database.share.publicDB.add(queryOperation)
}
}

class cloudkitHelper: ViewController{
static func request( error:Error, viewController:ViewController) {
    if let ckerror = error as? CKError {
        if ckerror.code == CKError.requestRateLimited {
            let retryInterval = ckerror.userInfo[CKErrorRetryAfterKey] as? TimeInterval
            DispatchQueue.main.async {
                Timer.scheduledTimer(timeInterval: retryInterval!, target: self, selector: #selector(self.getData), userInfo: nil, repeats: false)
            }
        }
        else if ckerror.code == CKError.zoneBusy {
            let retryInterval = ckerror.userInfo[CKErrorRetryAfterKey] as? TimeInterval
            DispatchQueue.main.async {
                Timer.scheduledTimer(timeInterval: retryInterval!, target: self, selector: #selector(self.getData), userInfo: nil, repeats: false)
            }
        }
        else if ckerror.code == CKError.limitExceeded {
            let retryInterval = ckerror.userInfo[CKErrorRetryAfterKey] as? TimeInterval
            DispatchQueue.main.async {
                Timer.scheduledTimer(timeInterval: retryInterval!, target: self, selector: #selector(self.getData), userInfo: nil, repeats: false)
            }
        }
}

2018-10-17 19：54：41.335517 + 0100 cloudkitApp [6011：1308502] + [cloudkitApp.cloudkitHelper getData]：无法识别的选择器已发送给类0x103879c28 2018-10-17 19：54：41.407939 + 0100 cloudkitApp [6011：1308502] ***由于未捕获而终止应用程序异常“ NSInvalidArgumentException”，原因： '+ [cloudkitApp.cloudkitHelper getData]：无法识别的选择器已发送至类别0x103879c28'

Answer 1

请阅读错误消息。

它表示getData中没有选择器cloudkitHelper，这是事实。请根据命名约定将其命名为CloudkitHelper，并表示您正在调用 class 方法。

getData属于ViewController，（目标）self代表CloudkitHelper类。

将Timer行更改为

Timer.scheduledTimer(timeInterval: retryInterval!, target: viewController, selector: #selector(getData), userInfo: nil, repeats: false)

与ViewController和实例方法相比，extension和实例方法更合理。我删除了冗余代码，并使用了基于块的Timer API

extension ViewController {
    func request( error:Error) {
        if let ckerror = error as? CKError {
            switch ckerror.code {
            case .requestRateLimited, .zoneBusy, .limitExceeded:
                let retryInterval = ckerror.userInfo[CKErrorRetryAfterKey] as! TimeInterval
                Timer.scheduledTimer(withTimeInterval: retryInterval, repeats: false) { _ in
                    DispatchQueue.main.async {
                        self.getData()
                    }
                }
            default: break
            }
        }
    }
}

处理cloudkit错误时未捕获的异常'NSInvalidArgumentException'

1 个答案: