ios - 创建Singleton，在ViewController中使用时出错？

我已经在一个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，它将对它下面的每个NSString引用引发错误。该错误显示为：“未知的类方法forStringForKey”和“未知的方法setString：forKey”。我在这里想念什么吗？我是否正确实施了单例？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

最佳答案

您实际上是在代码中弄乱了singleton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

无论您想在哪里使用CloudStore变量，都可以使用它，例如：

设定数据：

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

获取数据：

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

同步中：

[[[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。