iOS 10 CoreData使用总结。
Include Core Data
创建工程时选择包含CoreData，系统会自动生成相关文件。
Add Entity
在xcdatamodeld文件中，添加Entity。
Entity相当于表，其中Attributes相当于表中的记录，对应需要存储的数据。
Create NSManagedObject Subclass
创建Entity对应的model。
在Xcode8中，创建方式为Editor ———— Create NSManagedObject Subclass。
注意，创建之前需要将数据库的Codegen设置为Manual/None，否则会报duplicate错误。
Get NSPersistentContainer Object
iOS 10 对Core Data做了很大的优化和改进，大大简化了Core Data的使用。
NSPersistentContainer是新添加的类，从此大部分情况下无需再和NSManagedObjectContext、NSPersistentStoreCoordinator打交道。
获取NSPersistentContainer
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| #import 'AppDelegate.h'
@interface ViewController ()
@property(nonatomic, strong) NSPersistentContainer *container;
@end
@implementation ViewController
-(void)viewDidLoad{
[super viewDidLoad];
self.container = ((AppDelegate *)[UIApplication sharedApplication].delegate).persistentContainer;
}
@end
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Add Record
导入通过系统创建的Create NSManagedObject Subclass，通过NSEntityDescription增添记录。
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| #import "People+CoreDataProperties.h"
#define kEntityName @"People"
-(void)addRecord{
People *people = [NSEntityDescription insertNewObjectForEntityForName:kEntityName inManagedObjectContext:self.container.viewContext];
people.name = @"Tom";
people.sex = YES;
people.age = 23;
}
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Fetch Record
通过NSFetchRequest查询记录。
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| -(void)fetchRecord{
NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:kEntityName];
NSArray<People *> *results = [self.container.viewContext executeFetchRequest:fetchRequest error:nil];
for (People *people in results) {
NSLog(@"name %@", people.name);
NSLog(@"sex %@", people.sex);
NSLog(@"age %@", people.age);
}
}
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Update Record
先fetch需要修改的记录，然后直接修改即可。
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| -(void)updateRecord{
NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:kEntityName];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name == %@", @"Tom"];
fetchRequest.predicate = predicate;
NSArray<People *> *results = [self.container.viewContext executeFetchRequest:fetchRequest error:nil];
for (People *people in results) {
people.name = @"Lily";
}
}
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Delete Record
先fetch需要删除的记录，然后通过NSManagedObjectContext删除即可。
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| -(void)deleteRecord{
NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:kEntityName];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name == %@", @"Lily"];
fetchRequest.predicate = predicate;
NSArray<People *> *results = [self.container.viewContext executeFetchRequest:fetchRequest error:nil];
for (People *people in results) {
[self.container.viewContext deleteObject:people];
}
}
|
GitHub源码
CoreDataDemo