关于ios：无法从公共可变数组(Objective-C)中删除对象

Can't remove an object from public mutable array (Objective-C)

该程序理论上应通过单击来加载带有图像的随机字符串。这项工作正常，但我想添加一个从两个数组中删除当前对象的函数，因此我将所有数组和整数公开(对吗？)，并为数组制作了可变副本。然后我在底部写了三行，Xcode显示了这一点：

No visible @interface for 'NSArray' declares the selector
'removeObjectAtIndex'

这是什么意思？如何解决？

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#import"KotikViewController.h"

@interface KotikViewController (){
NSArray *movieNames;
NSArray *movieCovers;
NSArray *movieNamesMutableCopie;
NSArray *movieCoversMutableCopie;
NSInteger yourRandomIndex;
}

@end

@implementation KotikViewController

- (IBAction)showNewMovie:(id)sender {
movieNames =@[@"Побег из шаушенка", @"Бэтмен:Начало", @"Форрест Гамп"];
movieCovers= @[@"shawshank.jpg", @"batmanone.jpg", @"forrest.jpg"];
movieNamesMutableCopie=[movieNames mutableCopy];
movieCoversMutableCopie=[movieCovers mutableCopy];

//Setting a randomindex for movie
yourRandomIndex = arc4random_uniform(movieNamesMutableCopie.count);

//Getting imageName and movieName at randomIndex
NSString* movieName= movieNamesMutableCopie[yourRandomIndex];
NSString* movieCover= movieCoversMutableCopie[yourRandomIndex];

//Setting ImageView image and movieName in a label from strings
[_movieCover setImage:[UIImage imageNamed:movieCover]];
_movieName.text = movieName;
;
}

- (IBAction)alreadyWatched:(id)sender {
[movieNamesMutableCopie removeObjectAtIndex:yourRandomIndex];
}
@end

NSArray不是可变副本。即您不能添加或删除项目。您应该改用NSMutableArray。

您的私有变量(和公共变量？)应该像这样更改

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NSArray *movieNames;
NSArray *movieCovers;
NSMutableArray *movieNamesMutableCopie;
NSMutableArray *movieCoversMutableCopie;