Question

我有一个名为randomSelection的NSMutableArray：

NSMutableArray *randomSelection;

如果符合某些条件，我会尝试向此数组添加字符串：

[randomSelection addObject:@"string1"];

然后我尝试输出字符串，以确定它是否已添加它：

NSString *test = [randomSelection objectAtIndex:0];
NSLog(test);

然而，没有任何内容输出到错误日志，我无法弄清楚原因。

任何帮助/提示都表示赞赏。

Answer 1

我认为你缺少为数组分配内存。所以试试这个

NSMutableArray *randomSelection = [[NSMutableArray alloc] init];
[randomSelection addObject:@"string1"];
NSString *test = [randomSelection objectAtIndex:0];
NSLog(test);

Answer 2

NSMutableArray *randomSelection =  [[NSMutableArray alloc]init];
[randomSelection addObject:@"string1"];

您需要先分配它。

Answer 3

首先使用以下语句＆amp;分配数组。然后是对象。

NSMutableArray *randomSelection =  [[NSMutableArray alloc] init];
[randomSelection addObject:[NSString stringWithFormat:@"String1"]];
[randomSelection addObject:[NSString stringWithFormat:@"String2"]];
NSLog(@"Array - %@", randomSelection);

这肯定会解决你的问题。

Answer 4

只需分配你的NSMutableArray。你会解决你的问题。

Answer 5

试试这个：

NSMutableArray *randomSelection = [[NSMutableArray alloc]init]; 
[randomSelection addObject:@"string1"];

Answer 6

斯威夫特：

MapLoader.Listener mapLoaderListener = new MapLoader.Listener() {
  public void onUninstallMapPackagesComplete(MapPackage rootMapPackage,
     MapLoader.ResultCode mapLoaderResultCode) {
  }
  public void onProgress(int progressPercentage) {
  }
  public void onPerformMapDataUpdateComplete(MapPackage rootMapPackage,
     MapLoader.ResultCode mapLoaderResultCode) {
  }
  public void onInstallationSize(long diskSize, long networkSize) {
  }
  public void onInstallMapPackagesComplete(MapPackage rootMapPackage,
      MapLoader.ResultCode mapLoaderResultCode) {
  }
  public void onGetMapPackagesComplete(MapPackage rootMapPackage,
      MapLoader.ResultCode mapLoaderResultCode) {

      // This method will be called after MapLoader#getMapPackages()
      // is called
      // You can use the rootMapPackage object to find the Id's to
      // pass to installMapPackages()

  }
  public void onCheckForUpdateComplete(boolean updateAvailable,
    String currentMapVersion,String newestMapVersion,
          MapLoader.ResultCode mapLoaderResultCode) {
  }
};

MapLoader mapLoader = MapLoader.getInstance();

mapLoader.addListener(mapLoaderListener);
mapLoader.getMapPackages();

OR

var randomSelection: [AnyObject] = [AnyObject]()
randomSelection.append("string1")
let test: String = randomSelection[0] as! String
print(test)

如何将字符串对象添加到NSMutableArray

6 个答案: