Trying to render a tableview

AppDelegate.m

//
//  AppDelegate.m
//  Tableview3
//
//  Created by Kevin Gutowski on 5/23/19.
//  Copyright © 2019 Kevin. All rights reserved.
//

#import "AppDelegate.h"

@interface AppDelegate () <NSTableViewDataSource>
@end

@implementation AppDelegate

-(NSArray *)dataArray
{
    NSArray *array = [NSArray arrayWithObjects:
                      [NSDictionary dictionaryWithObjectsAndKeys:@"1001",@"key1",@"1002",@"key2",@"1003",@"key3",@"1004",@"key4",@"1005",@"key5",@"1006",@"key6",@"1007",@"key7", nil],
                      [NSDictionary dictionaryWithObjectsAndKeys:@"2001",@"key1",@"2002",@"key2",@"2003",@"key3",@"2004",@"key4",@"2005",@"key5",@"2006",@"key6",@"2007",@"key7", nil],
                      [NSDictionary dictionaryWithObjectsAndKeys:@"3001",@"key1",@"3002",@"key2",@"3003",@"key3",@"3004",@"key4",@"3005",@"key5",@"3006",@"key6",@"3007",@"key7", nil],
                      [NSDictionary dictionaryWithObjectsAndKeys:@"4001",@"key1",@"4002",@"key2",@"4003",@"key3",@"4004",@"key4",@"4005",@"key5",@"4006",@"key6",@"4007",@"key7", nil],
                      nil];
    return array;
}

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
    // Insert code here to initialize your application
    NSWindow *window = [[NSApplication sharedApplication] mainWindow];
    
    NSScrollView* scrollView = [[NSScrollView alloc] initWithFrame:[[window contentView] bounds]];
    [scrollView setBorderType:NSBezelBorder];
    [scrollView setHasVerticalScroller:YES];
    [scrollView setHasHorizontalScroller:YES];
    [scrollView setAutohidesScrollers:NO];
    
    NSRect clipViewBounds = [[scrollView contentView] bounds];
    NSTableView* tableView = [[NSTableView alloc] initWithFrame:clipViewBounds];
    
    NSTableColumn* firstColumn = [[NSTableColumn alloc] initWithIdentifier:@"firstColumn"];
    [[firstColumn headerCell] setStringValue:@"First"];
    [tableView addTableColumn:firstColumn];
    
    NSTableColumn* secondColumn = [[NSTableColumn alloc] initWithIdentifier:@"secondColumn"];
    [[secondColumn headerCell] setStringValue:@"Second"];
    [tableView addTableColumn:secondColumn];
    
    [tableView setDataSource:self];
    [scrollView setDocumentView:tableView];
    
    [[window contentView] addSubview:scrollView];
    
}

-(id) tableView:(NSTableView *)aTableView objectValueForTableColumn:(nullable NSTableColumn *)tableColumn row:(NSInteger)row {
    NSString *aString;
    aString = [[[self dataArray] objectAtIndex:row] objectForKey:tableColumn];
    return aString;
}

-(NSInteger)numberOfRowsInTableView:(NSTableView *)tableView {
    NSInteger recordCount = [[self dataArray] count];
    return recordCount;
}


- (void)applicationWillTerminate:(NSNotification *)aNotification {
    // Insert code here to tear down your application
}

@end