iOS OC 写一个实现每日步数，详细代码

在iOS中创建一个基本的应用程序，用于每天追踪用户的步数，并保存数据，你可以使用Core Data来持久化数据，结合HealthKit获取实时步数。这里提供一个简化的示例代码：

首先，确保导入所需的框架：

#import <UIKit/UIKit.h>
#import <HealthKit/HealthKit.h>
#import <CoreData/CoreData.h>

创建一个模型（Model）文件，例如`StepsManagedObject`，包含属性如`date`和`steps`：

// 如果你是Swift开发者，这里用Swift写
struct StepsManagedObject {
    @NSManaged var date: Date
    @NSManaged var steps: Int16
}

// Objective-C版
@interface StepsManagedObject : NSManagedObject

@property (nonatomic, strong, readonly) NSDate *date;
@property (nonatomic, assign) short steps;

@end

然后在`AppDelegate.m`中设置HealthKit并初始化Core Data：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // 开启HealthKit权限
    [self requestHealthKitPermission];

    // 初始化Core Data
    [self configureCoreData];

    return YES;
}

- (void)requestHealthKitPermission {
    // 请求步数读取权限
    HKHealthStore *healthStore = [[HKHealthStore alloc] init];
    [healthStore requestAuthorizationToShareTypes:nil readTypes:@[HKObjectTypeStepCount] completion:^(BOOL granted, NSError * _Nullable error) {
        if (granted) {
            self.healthStore = healthStore;
        }
    }];
}

- (void)configureCoreData {
    // ...省略Core Data配置代码
}

在某个视图控制器里实现步数的获取和存储：

- (void)fetchDailySteps {
    NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"StepsManagedObject"];
    fetchRequest.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"date" ascending:YES]];
    
    NSError *error = nil;
    NSArray *stepsObjects = [self.coreData.managedObjectContext executeFetchRequest:fetchRequest error:&error];
    
    if (!error) {
        // 如果存在当天的步数，更新；否则添加新的
        if ([stepsObjects count]) {
            StepsManagedObject *lastStep = stepsObjects.lastObject;
            if ([lastStep.date isEqualToDate:[NSDate date]]) {
                // 更新步数
                lastStep.steps += [self getTodayStepsFromHealthKit];
            } else {
                // 添加新的条目
                StepsManagedObject *newStep = [NSEntityDescription insertNewObjectForEntityForName:@"StepsManagedObject" inManagedObjectContext:self.coreData.managedObjectContext];
                newStep.date = [NSDate date];
                newStep.steps = [self getTodayStepsFromHealthKit];
            }
        } else {
            // 如果第一天，直接添加
            StepsManagedObject *newStep = [NSEntityDescription insertNewObjectForEntityForName:@"StepsManagedObject" inManagedObjectContext:self.coreData.persistentContainer.viewContext];
            newStep.date = [NSDate date];
            newStep.steps = [self getTodayStepsFromHealthKit];
        }

        // 保存到Core Data
        NSError *saveError = nil;
        if (![self.coreData.saveContext save:&saveError]) {
            NSLog(@"Error saving steps: %@", saveError);
        }
    } else {
        NSLog(@"Error fetching steps: %@", error);
    }
}

- (NSInteger)getTodayStepsFromHealthKit {
    // 这里使用HealthKit获取今天的步数，代码类似上文的getStepsForDate:方法
    // ...
    return steps; // 返回步数
}

这只是一个基础的示例，实际项目中可能需要添加更多的错误处理和UI交互。同时请注意，由于篇幅原因，`getTodayStepsFromHealthKit`方法未给出完整细节，你需要根据HealthKit的API来获取步数。