之前看关于CoreData的使用都w是很早之前的，对于现在有些不太适用，在网上各种查找和总结之后，写了这篇文章，有兴趣的朋友可以看看。
1.创建工程的时候选择CoreData（不建议）
CoreData
创建工程的是选择了CoreData，创建完工程之后，系统会自动生成该文件
你也可以通过添加文件达到同样的效果
选中文件，往里面添加你想要添加的模型，并对属性进行设置
(ps:Entity首字母必须大写，属性类型也需要规范设置)
创建实体模型
每个模型对应四个文件
2.创建你的Manager类-继承自NSObject
.h文件
#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>
@interface MyCoreManager : NSObject
/**管理对象, 上下文, 持久性存储模型对象*/
@property (nonatomic, strong) NSManagedObjectContext *managedObjectContext;
/**单例*/
+ (instancetype)shareInstanceWithStoreName:(NSString *)storeName;
/** 查找 数据*/
- (NSMutableArray *)findByModel:(id)model predicateString: (NSString *)predicateString;
/** 插入 数据 */
- (BOOL)insertModel:(id)model;
/** 删除 数据 */
- (BOOL)removeModel:(id)model predicateString: (NSString *)predicateString;
/** 修改 数据 */
- (BOOL)changeModel:(id)model predicateString: (NSString *)predicateString;
@end
.m文件
#import "MyCoreManager.h"
#import <CoreData/CoreData.h>
#import <objc/runtime.h>
#define Class_NAME(CName) NSStringFromClass([CName class])
@interface MyCoreManager ()
/**被管理的数据模型, 数据结构*/
@property (nonatomic, strong) NSManagedObjectModel *managedObjectModel;
/**连接数据库的*/
@property (nonatomic, strong) NSPersistentStoreCoordinator *persistentStoreCoordinator;
/**数据库名*/
@property (nonatomic, strong) NSString *storeName;
@end
static MyCoreManager *coreData;
@implementation MyCoreManager
- (NSManagedObjectContext *)managedObjectContext
{
if (!_managedObjectContext) {
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (coordinator) {
_managedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];
[_managedObjectContext setPersistentStoreCoordinator:coordinator];
}
}
return _managedObjectContext;
}
// managedObjectModel 懒加载
- (NSManagedObjectModel *)managedObjectModel
{
if (!_managedObjectModel) {
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:_storeName withExtension:@"momd"];
_managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
}
return _managedObjectModel;
}
// persistentStoreCoordinator 懒加载
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
if (!_persistentStoreCoordinator) {
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:[NSString stringWithFormat:@"%@.sqlite", _storeName]];
NSLog(@"---\nstoreURL: %@",storeURL);
NSError *error = nil;
_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
abort();
}
}
return _persistentStoreCoordinator;
}
// Returns the URL to the application's Documents directory.获取Documents路径
- (NSURL *)applicationDocumentsDirectory
{
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}
#pragma mark - Methods
// 查
- (NSArray *)findByModel:(id)model predicateString: (NSString *)predicateString
{
NSError *error = nil;
NSArray *listArray = [_managedObjectContext executeFetchRequest:[self fetchRequest:Class_NAME(model) predicate:predicateString] error:&error];
NSMutableArray *resultArray = [[NSMutableArray alloc] initWithArray:listArray];;
//
// if (listArray.count >= 1)
// {
//
// for (NSManagedObject *manager in listArray)
// {
//
// for (NSString *propertyName in [self ClassAttributes:model] )
// {
// [manager setValue:[model valueForKey:propertyName] forKey:propertyName];
// }
// [resultArray addObject:model];
// }
// }
return resultArray;
}
// 插入 数据
- (BOOL)insertModel:(id)model
{
NSManagedObject *manager = [NSEntityDescription insertNewObjectForEntityForName:Class_NAME(model) inManagedObjectContext:_managedObjectContext];
for (NSString *propertyName in [self ClassAttributes:model]) {
[manager setValue:[model valueForKey:propertyName] forKey:propertyName];
}
BOOL result = [self saveContext];
return result;
}
// 删除 数据
- (BOOL)removeModel:(id)model predicateString: (NSString *)predicateString
{
NSError * error = nil;
NSArray * listArray = [_managedObjectContext executeFetchRequest:[self fetchRequest:Class_NAME(model) predicate:predicateString] error:&error];
if (listArray.count > 0) {
for (NSManagedObject *manager in listArray) {
[_managedObjectContext deleteObject:manager];
}
}
return [self saveContext];
}
// 改
- (BOOL)changeModel:(id)model predicateString: (NSString *)predicateString
{
NSError * error = nil;
NSArray * listArray = [_managedObjectContext executeFetchRequest:[self fetchRequest:Class_NAME(model) predicate:predicateString] error:&error];
if (listArray.count > 0) {
for (NSManagedObject * manager in listArray) {
for (NSString * propertyName in [self ClassAttributes:model]) {
[manager setValue:[model valueForKey:propertyName] forKey:propertyName];
}
}
}
return [self saveContext];
}
// 读取数据请求 ( 连接 请求 )
- (NSFetchRequest *)fetchRequest:(NSString *)entityName predicate:(NSString *)predicateString
{
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:[NSEntityDescription entityForName:entityName inManagedObjectContext:_managedObjectContext]];
if (predicateString != nil) {
NSPredicate *predicate = [NSPredicate predicateWithFormat:predicateString];
[request setPredicate:predicate];
}
return request;
}
#pragma mark - allAttributes
- (NSMutableArray *)ClassAttributes:(id)classModel
{
NSMutableArray *array = [NSMutableArray array];
NSString *className = Class_NAME(classModel);
const char *cClassName = [className UTF8String];
id classM = objc_getClass(cClassName);
unsigned int outCount, i;
objc_property_t * properties = class_copyPropertyList(classM, &outCount);
for (i = 0; i < outCount; i++) {
objc_property_t property = properties[i];
NSString * attributeName = [NSString stringWithUTF8String:property_getName(property)];
[array addObject:attributeName];
}
return array;
}
#pragma mark - save
- (BOOL)saveContext
{
NSManagedObjectContext *context = [self managedObjectContext];
if (context) {
NSError *error = nil;
if ([context hasChanges] && ![context save:&error]) {
abort();
return NO;
}
}
return YES;
}
// 单例
+ (instancetype)shareInstanceWithStoreName:(NSString *)storeName
{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
coreData = [[self alloc] init];
coreData.storeName = storeName;
});
return coreData;
}
@end
3.调用
1.引入模型文件，和你创建的模型名字相同的那个
2.引入你的管理类
增
MyCoreManager * coreData = [MyCoreManager shareInstanceWithStoreName:@"MyData"];
Student * stu = [[Student alloc]initWithEntity:[NSEntityDescription entityForName:@"Student" inManagedObjectContext:coreData.managedObjectContext] insertIntoManagedObjectContext:nil];
stu.name = @"alex";
stu.age = @"12";
[coreData insertModel:stu];
查
MyCoreManager * coreData = [MyCoreManager shareInstanceWithStoreName:@"MyData"];
Student * stu = [[Student alloc]initWithEntity:[NSEntityDescription entityForName:@"Student" inManagedObjectContext:coreData.managedObjectContext] insertIntoManagedObjectContext:nil];
NSMutableArray * StuArr = [coreData findByModel:stu predicateString:@"name = 12 AND age = 12"];
for (Student * stuModel in StuArr) {
MyModel * model = [[MyModel alloc]init];
model.name = stuModel.name;
model.age = stuModel.age;
[_datas addObject: model];
}
//删
- (BOOL)removeModel:(id)model predicateString: (NSString *)predicateString
//改
- (BOOL)changeModel:(id)model predicateString: (NSString *)predicateString
三点要注意：
(1) shareInstanceWithStoreName:@"MyData"]中的MyData是你所创建的model文件名
(2) 对象初始化不能简单的alloc init ,需要按上面代码的歌声进行初始化，否则调用对象就会导致程序崩溃
(3)谓词（predicateString）的使用，不懂的同学可以戳这里http://www.jianshu.com/p/3da75e023b9c
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