(lldb) error swift NSMutableArray

Question

我试图创建一个有趣的事实应用程序。它每次从数组中显示一个随机字符串，然后从数组中删除该事实。对于我的代码，当应用程序首次启动时，它获得新的事实数组，并在应用程序关闭时保存数据，并在初始启动后每次使用上次启动时的数组。我的问题是我得到"线程1:信号SIGABRT"当我试图从我的数组中删除一个字符串在我的最后一行。请告诉我需要做哪些修改。我对编程还是个新手。我很感激我得到的所有帮助。谢谢你的宝贵时间。

import Foundation
let userDefaults = NSUserDefaults.standardUserDefaults()
func isAppAlreadyLaunchedOnce()->Bool{
    let defaults = NSUserDefaults.standardUserDefaults()
    if let isAppAlreadyLaunchedOnce = defaults.stringForKey("isAppAlreadyLaunchedOnce"){
        println("App already launched")
        return true
    }
    else{
        defaults.setBool(true, forKey: "isAppAlreadyLaunchedOnce")
        println("App launched first time")
        return false
    }
}
struct newFactBook {

    let factsArray : NSMutableArray = [
        "Ants stretch when they wake up in the morning.",
        "Ostriches can run faster than horses.",
        "Olympic gold medals are actually made mostly of silver.",
        "You are born with 300 bones; by the time you are an adult you will have 206.",
        "It takes about 8 minutes for light from the Sun to reach Earth.",
        "Some bamboo plants can grow almost a meter in just one day.",
        "The state of Florida is bigger than England.",
        "Some penguins can leap 2-3 meters out of the water.",
        "On average, it takes 66 days to form a new habit.",
        "Mammoths still walked the earth when the Great Pyramid was being built."]
}
var checkLaunch = isAppAlreadyLaunchedOnce()
var oldFunFactsArray : NSMutableArray = []
if(checkLaunch == false){
    oldFunFactsArray = newFactBook().factsArray.mutableCopy() as! NSMutableArray
}
else if (checkLaunch == true){
    oldFunFactsArray = userDefaults.objectForKey("key") as! NSMutableArray
}


func randomFacts1() -> (String, Int){
    var unsignedArrayCount = UInt32(oldFunFactsArray.count)
    var unsignedRandomNumber = arc4random_uniform(unsignedArrayCount)
    var randomNumber = Int(unsignedRandomNumber)
    return (oldFunFactsArray[randomNumber] as! String, randomNumber)
}
oldFunFactsArray.removeObjectAtIndex(randomFacts1().1) // Thread 1: signal SIGABRT
userDefaults.setObject(oldFunFactsArray, forKey:"key")
userDefaults.synchronize()
println(oldFunFactsArray)

这是我在调试区得到的:

App already launched
2015-09-02 10:17:06.110 TestCode1[36860:1553790] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '-[__NSCFArray removeObjectAtIndex:]: mutating method sent to immutable object'
*** First throw call stack:
(
    0   CoreFoundation                      0x00007fff8245403c __exceptionPreprocess + 172
    1   libobjc.A.dylib                     0x00007fff8743d76e objc_exception_throw + 43
    2   CoreFoundation                      0x00007fff82453eed +[NSException raise:format:] + 205
    3   CoreFoundation                      0x00007fff824477be -[__NSCFArray removeObjectAtIndex:] + 94
    4   TestCode1                           0x00000001001552a6 main + 806
    5   libdyld.dylib                       0x00007fff903bd5c9 start + 1
    6   ???                                 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb) 

Answer 1

我是这样做的:

var modArray = oldFunFactsArray.mutableCopy() as! NSMutableArray
modArray.removeObjectAtIndex(randomFacts1().1)
oldFunFactsArray = modArray

我创建了一个新的数组并将它赋值给我的旧数组。然后我从我的新数组中删除字符串，并将我的旧数组分配给我的新数组。谢谢大家的帮助!

Answer 2

即使一切设置正确，有时Xcode给我们一个NSArray而不是NSMutableArray。要取回一个NSMutableArray，这样你就可以移除对象了，这样做:

let immutable = array.mutableCopy() as! NSMutableArray