ios - 单例创建，在 ViewController 中使用时出错？

Question

我在一个 ViewController (PointsViewController.m) 中将 NSUbiquitousKeyValueStore 定义为“CloudStore”，并创建了一个 CloudStore 单例，以便能够在另一个 ViewController (PayViewController.m) 中使用它。

但是，当我在 PayViewController.m 中调用 Singleton 时，它会在其下的每个 NSString 引用上引发错误。错误内容为:“没有已知的 StringForKey 类方法”和“没有已知的 setString:forKey 方法”。我在这里错过了什么吗？我是否错误地实现了单例？请参阅下面的 ViewController 和 Singleton 代码。

PointsViewController.m

 NSUbiquitousKeyValueStore *CloudStore = [NSUbiquitousKeyValueStore defaultStore];

               NSString *pointsStr = [CloudStore stringForKey:@"UserWantsToBuyPoints"];
               [CloudStore setString:pointsStr forKey:@"UserWantsToBuyPoints"];
               [CloudStore synchronize];


                NSString *TotalUserPoints = [CloudStore stringForKey:@"TotalUserPoints"];


                int pointsInt = [pointsStr intValue];
                int TotalUserPointsInt = [TotalUserPoints intValue];


                TotalUserPointsInt = TotalUserPointsInt + pointsInt;

                NSString *totalStr = [NSString stringWithFormat:@"%d", TotalUserPointsInt];

                [CloudStore setObject:totalStr forKey:@"TotalUserPoints"];
                [CloudStore synchronize];

PayViewController.m

[CloudStore singleton];

        NSString *pointsStr = [CloudStore stringForKey:@"UserWantsToBuyPoints"];
        [CloudStore setString:pointsStr forKey:@"UserWantsToBuyPoints"];
        [cloudStore synchronize];


        NSString *TotalUserPoints = [CloudStore stringForKey:@"TotalUserPoints"];


        int pointsInt = [pointsStr intValue];
        int TotalUserPointsInt = [TotalUserPoints intValue];


        TotalUserPointsInt = TotalUserPointsInt + pointsInt;

        NSString *totalStr = [NSString stringWithFormat:@"%d", TotalUserPointsInt];

        [CloudStore setObject:totalStr forKey:@"TotalUserPoints"];
        [CloudStore synchronize];
       NSString *pointsStr = [CloudStore stringForKey:@"UserWantsToBuyPoints"];
       [CloudStore setString:pointsStr forKey:@"UserWantsToBuyPoints"];
       [CloudStore synchronize];


        NSString *TotalUserPoints = [CloudStore stringForKey:@"TotalUserPoints"];


        int pointsInt = [pointsStr intValue];
        int TotalUserPointsInt = [TotalUserPoints intValue];


        TotalUserPointsInt = TotalUserPointsInt + pointsInt;

        NSString *totalStr = [NSString stringWithFormat:@"%d", TotalUserPointsInt];

        [CloudStore setObject:totalStr forKey:@"TotalUserPoints"];
        [CloudStore synchronize];

CloudStore.h(单例)

#import <Foundation/Foundation.h>

@interface CloudStore : NSObject

+(CloudStore *)singleton;

@end

CloudStore.m(单例)

#import "CloudStore.h"

@implementation CloudStore

+(CloudStore *)singleton {
    static dispatch_once_t pred;
    static CloudStore *shared = nil;
    dispatch_once(&pred, ^{
        shared = [[CloudStore alloc] init];
    });
    return shared;
}

@end

Answer 1

您实际上是在搞乱代码中的单例和 iCloud 存储对象。您需要在单例中声明并初始化 iCloud 对象并使用它:

CloudStore.h

#import <Foundation/Foundation.h>

@interface CloudStore : NSObject

// Storage property
@property (nonatomic, strong) NSUbiquitousKeyValueStore *cloud;

+ (CloudStore *)sharedStorage;

@end

CloudStore.m

#import "CloudStore.h"

@implementation CloudStore

+ (CloudStore *)sharedStorage
{
    static dispatch_once_t pred;
    static CloudStore *shared = nil;
    dispatch_once(&pred, ^{
        shared = [[CloudStore alloc] init];
        [shared initStorage];
    });
    return shared;
}

- (void)initStorage
{
   cloud = [NSUbiquitousKeyValueStore defaultStore];
}
@end

无论您想在何处使用 CloudStore 变量，都可以像这样使用它:

设置数据:

[[[CloudStore sharedStorage] cloud] setObject:totalStr forKey:@"TotalUserPoints"];

获取数据:

 NSString *pointsStr = [[[CloudStore sharedStorage] cloud] stringForKey:@"UserWantsToBuyPoints"];

同步:

[[[CloudStore sharedStorage] cloud] synchronize];

您应该阅读这个不错的教程:iOS Design Patterns ，它将帮助您更好地理解单例的用法。