數據存儲：CoreData

時間 2019-12-05

標籤數據存儲 coredata 简体版

原文原文鏈接

CoreData的簡單使用介紹（已User表爲例）

重點類z

NSManagedObject

經過Core Data從數據庫中取出的對象,默認狀況下都是NSManagedObject對象.
NSManagedObject的工做模式有點相似於NSDictionary對象,經過鍵-值對來存取全部的實體屬性.
setValue:forkey:存儲屬性值(屬性名爲key);
valueForKey:獲取屬性值(屬性名爲key). 每一個NSManagedObject都知道本身屬於哪一個NSManagedObjectContextsql

NSManagedObjectContext：管理對象上下文

負責數據和應用庫之間的交互(CRUD，即增刪改查、保存等接口都在這個對象中).
全部的NSManagedObject都存在於NSManagedObjectContext中，因此對象和context是相關聯的
每一個 context 和其餘 context 都是徹底獨立的
每一個NSManagedObjectContext都知道本身管理着哪些NSManagedObject數據庫

NSManagedObjectModel：模型對象

Core Data的模型文件bash

NSPersistentStoreCoordinator：存儲調度器

添加持久化存儲庫，CoreData的存儲類型（好比SQLite數據庫就是其中一種）
中間審查者，用來將對象圖管理部分和持久化部分捆綁在一塊兒，負責相互之間的交流（中介同樣）fetch

NSEntityDescription：

用來描述實體：至關於數據庫表中一組數據描述ui

User中字段

@property (nonatomic) int16_t age;
@property (nonatomic) int64_t id;
@property (nullable, nonatomic, copy) NSString *name;
@property (nonatomic) BOOL sex;
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系統庫

#import <CoreData/CoreData.h>
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打開數據庫

// 建立數據庫
    // 1. 實例化數據模型(將全部定義的模型都加載進來)
    // merge——合併
    self.managedObjectModel = [NSManagedObjectModel mergedModelFromBundles:nil];
    
    // 2. 實例化持久化存儲調度，要創建起橋樑，須要模型
    self.persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:self.managedObjectModel];
    
    // 3. 添加一個持久化的數據庫到存儲調度
    // 3.1 創建數據庫保存在沙盒的URL
    NSString *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).lastObject;
    NSString *filePath = [[path stringByAppendingString:@"/"] stringByAppendingString:@"wudan.sqlite"];
    NSURL *pathUrl = [NSURL fileURLWithPath:filePath];
    
    // 3.2 打開或者新建數據庫文件
    // 若是文件不存在，則新建以後打開
    // 否者直接打開數據庫
    NSError *error;
    @try {
        [self.persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:pathUrl options:nil error:&error];
        self.context = [[NSManagedObjectContext alloc] init];
        self.context.persistentStoreCoordinator = self.persistentStoreCoordinator;
    } @catch (NSException *exception) {
        NSLog(@"Error:%@",error);
    } @finally {
        NSLog(@"打開數據庫");
    }
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查詢數據

所有查詢

- (void)queryAllResult:(void(^)(NSArray *dataArray))result {
    NSMutableArray *array = [NSMutableArray array];
    
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"id > 0"];
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"User"];
    request.predicate = predicate;
    NSError *error;
    
    NSArray *re = [self.context executeFetchRequest:request error:&error];
    if (re.count != 0) {
        for (User *user in re) {
            [array addObject:user];
        }
    }
    result(array);
}
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分頁查詢

- (void)queryUserInfoWithPageNo:(NSInteger)pageNo pageSize:(NSInteger)pageSize result:(void(^)(NSArray *dataArray))result {
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"User"];
    NSSortDescriptor *scoreSort = [NSSortDescriptor sortDescriptorWithKey:@"id" ascending:true];
    request.sortDescriptors = @[scoreSort];
    request.fetchOffset = (pageNo - 1) * pageSize;
    request.fetchLimit = pageSize;
    
    NSError *error = nil;
    NSArray *re = [self.context executeFetchRequest:request error:&error];
    NSMutableArray *array = [NSMutableArray array];
    
    if (re.count != 0) {
        for (User *user in re) {
            [array addObject:user];
        }
    }
    result(array);
}
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條件查詢

- (void)queryUserInfoByObject:(id)object value:(id)value result:(void(^)(NSArray *dataArray))result  {
    NSMutableArray *array = [NSMutableArray array];
    
    NSPredicate *predicate = [NSPredicate predicateWithFormat:[NSString stringWithFormat:@"%@ = '%@'", object, value]];
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"User"];
    request.predicate = predicate;
    NSError *error;
    
    NSArray *re = [self.context executeFetchRequest:request error:&error];
    if (re.count != 0) {
        for (User *user in re) {
            [array addObject:user];
        }
    }
    result(array);
}
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新增數據

- (void)addUserInfo:(NSInteger)userId name:(NSString *)name sex:(BOOL)sex age:(NSInteger)age success:(void(^)(void))success fail:(void(^)(void))fail {
    
    __block NSArray *array;
     [self queryUserInfoByObject:@"id" value:@(userId) result:^(NSArray * _Nonnull dataArray) {
         array = dataArray;
     }];
    
    if (array.count == 0) {
        
        User *user = [NSEntityDescription insertNewObjectForEntityForName:@"User" inManagedObjectContext:self.context];
        user.name = name;
        user.id = userId;
        user.sex = sex;
        user.age = age;
        
        NSError *error;

        @try {
            [self.context save:&error];
            success();
        } @catch (NSException *exception) {
            NSLog(@"%@", error);
            fail();
        } @finally {
            NSLog(@"新增");
        }
    } else {
        fail();
    }
}
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更新數據

- (void)updateUserInfo:(NSInteger)userId infoDic:(NSDictionary *)dic success:(void(^)(void))success fail:(void(^)(void))fail {
    NSPredicate *predicate = [NSPredicate predicateWithFormat:[NSString stringWithFormat:@"id = %ld", userId]];
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"User"];
    request.predicate = predicate;
    NSError *error;
    
    if (dic.count > 0) {
        NSArray *re = [self.context executeFetchRequest:request error:&error];
        if (re.count > 0) {
            for (User *user in re) {
                [dic enumerateKeysAndObjectsUsingBlock:^(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {
                    [user setValue:obj forKey:key];
                }];
            }
        }
        
        @try {
            [self.context save:&error];
            success();
        } @catch (NSException *exception) {
            NSLog(@"%@", error);
            fail();
        } @finally {
            NSLog(@"更新");
        }
    }
}
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刪除數據

- (void)deleteUserInfo:(NSInteger)userId success:(void(^)(void))success fail:(void(^)(void))fail {
    NSPredicate *predicate = [NSPredicate predicateWithFormat:[NSString stringWithFormat:@"id = %ld", userId]];
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"User"];
    request.predicate = predicate;
    NSError *error;
    
    NSArray *re = [self.context executeFetchRequest:request error:&error];
    if (re.count > 0) {
        @try {
            [self.context deleteObject:re.firstObject];
            [self.context save:nil];
            success();
        } @catch (NSException *exception) {
            NSLog(@"%@", error);
            fail();
        } @finally {
            NSLog(@"刪除數據");
        }
    } else {
        NSLog(@"數據庫中暫無該數據");
        fail();
    }
}
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