#import "Manager.h"

// This is the variable of interest!
static Manager *sharedManager = nil;

@implementation Manager

+ (instancetype)sharedManager
{
    return sharedManager;
}

+ (void)setManager:(Manager *)manager
{
    sharedManager = manager;
}

@end

- (void)viewDidLoad {
    [super viewDidLoad];
    Manager *tempManager = [[Manager alloc] init];
    [Manager setManager:tempManager];
}

- (void)testManager {
    // 1
    ViewController *vc = [[ViewController alloc] init];

    // 2
    NSLog(@"manager %@", [Manager sharedManager]);

    Manager *tempManager = [[Manager alloc] init];
    [Manager setManager:tempManager];

    // 3
    NSLog(@"manager %@", [Manager sharedManager]);
    [vc viewDidLoad];

    // 4
    NSLog(@"manager %@", [Manager sharedManager]);
}