ios - 类名的 NSString 占位符

Question

如何使用占位符作为类名？我有基于传入参数的方法，这些方法按名称引用其他类。在下面的粗略示例中，我需要能够仅根据名称加载三个 ViewController 之一(不是 ViewController 数组，因为这只是一个示例)。

-(void)loadViewController:(int)vcNumberToLoad
{
    NSString *vcOne = @"firstViewControllerName";
    NSString *vcTwo = @"secondViewControllerName";
    NSString *vcThree = @"thirdViewControllerName";

    NSArray *vcArray = [NSArray arrayWithObjects:vcOne, vcTwo, vcThree, nil];

    NSString *nameOfVCToLoad = [vcArray objectAtIndex:vcNumberToLoad];

    UIViewController |VALUE OF nameOfVCToLoad| = [[UIViewController alloc] init]; // What is the code to get the value of nameOfVCToLoad to be used as the instance name of the UIVC class
    [self.navigationController pushViewController:|VALUE OF nameOfVCToLoad| animated:NO];

}

例如，如果该方法使用参数“1”运行

NSString *nameOfVCToLoad = [vcArray objectAtIndex:vcNumberToLoad]; //this would = secondViewControllerName

UIViewController secondViewControllerName = [[UIViewController alloc] init];
[self.navigationController pushViewController:secondViewControllerName animated:NO];

其他问题似乎表明 [NSClassFromString:nameOfVCToLoad] 可能符合我的需要，如果是的话如何？

Answer 1

您对对象感到困惑。你在找这个

NSClassFromString(vcOne) 将帮助您进行动态类选择

isKindOfClass 将帮助您识别该类是否为给定类

-(void)loadViewController:(int)vcNumberToLoad
{
    NSString *vcOne = @"firstViewControllerName";
    NSString *vcTwo = @"secondViewControllerName";
    NSString *vcThree = @"thirdViewControllerName";


    firstViewControllerName *fvc = nil;
    secondViewControllerName *svc = nil;
    thirdViewControllerName *tvc = nil;


    NSArray *vcArray = [NSArray arrayWithObjects:vcOne, vcTwo, vcThree, nil];

    NSString *nameOfVCToLoad = [vcArray objectAtIndex:vcNumberToLoad];


    UIViewController *aLoadedViewController = [[NSClassFromString(nameOfVCToLoad) alloc] init];

    if ([aLoadedViewController isKindOfClass:[NSClassFromString(vcOne)]]) {

        fvc = aLoadedViewController;

    }
    else if ([aLoadedViewController isKindOfClass:[NSClassFromString(vcTwo)]]) {

        svc = aLoadedViewController;

    }
    else if ([aLoadedViewController isKindOfClass:[NSClassFromString(vcThree)]]) {

        tvc = aLoadedViewController;

    }

    [self.navigationController pushViewController:aLoadedViewController animated:NO];

}