CoreData的簡單使用介紹（已User表為例）
重點類z
- NSManagedObject
通過Core Data從資料庫中取出的物件,預設情況下都是NSManagedObject物件.
NSManagedObject的工作模式有點類似於NSDictionary物件,通過鍵-值對來存取所有的實體屬性.
setValue:forkey:儲存屬性值(屬性名為key);
valueForKey:獲取屬性值(屬性名為key). 每個NSManagedObject都知道自己屬於哪個NSManagedObjectContext
- NSManagedObjectContext：管理物件上下文
負責資料和應用庫之間的互動(CRUD，即增刪改查、儲存等介面都在這個物件中).
所有的NSManagedObject都存在於NSManagedObjectContext中，所以物件和context是相關聯的
每個 context 和其他 context 都是完全獨立的
每個NSManagedObjectContext都知道自己管理著哪些NSManagedObject
- NSManagedObjectModel：模型物件
Core Data的模型檔案
- NSPersistentStoreCoordinator：儲存排程器
新增持久化儲存庫，CoreData的儲存型別（比如SQLite資料庫就是其中一種）
中間審查者，用來將物件圖管理部分和持久化部分捆綁在一起，負責相互之間的交流（中介一樣）
- NSEntityDescription：
用來描述實體：相當於資料庫表中一組資料描述
User中欄位
@property (nonatomic) int16_t age;
@property (nonatomic) int64_t id;
@property (nullable, nonatomic, copy) NSString *name;
@property (nonatomic) BOOL sex;
複製程式碼系統庫
#import <CoreData/CoreData.h>
複製程式碼開啟資料庫
// 建立資料庫
// 1. 例項化資料模型(將所有定義的模型都載入進來)
// merge——合併
self.managedObjectModel = [NSManagedObjectModel mergedModelFromBundles:nil];
// 2. 例項化持久化儲存排程，要建立起橋樑，需要模型
self.persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:self.managedObjectModel];
// 3. 新增一個持久化的資料庫到儲存排程
// 3.1 建立資料庫儲存在沙盒的URL
NSString *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).lastObject;
NSString *filePath = [[path stringByAppendingString:@"/"] stringByAppendingString:@"wudan.sqlite"];
NSURL *pathUrl = [NSURL fileURLWithPath:filePath];
// 3.2 開啟或者新建資料庫檔案
// 如果檔案不存在，則新建之後開啟
// 否者直接開啟資料庫
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(@"開啟資料庫");
}
複製程式碼查詢資料
-
全部查詢
- (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);
}
複製程式碼-
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);
}
複製程式碼-
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);
}
複製程式碼新增資料
- (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();
}
}
複製程式碼更新資料
- (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");
}
}
}
複製程式碼刪除資料
- (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(@"刪除資料");
}
} else {
NSLog(@"資料庫中暫無該資料");
fail();
}
}
複製程式碼