CoreData简单教学（二）

1.CoreData 编写方便， 管理方便， 出错不易寻找， 整体性强， 关联性强

2.简单介绍查询的办法

 1 #pragma mark -
 2 - (NSMutableArray *) findAll {
 3     NSManagedObjectContext * cxt = [self managedObjectContext];
 4
 5     NSEntityDescription * entityDescription = [NSEntityDescription entityForName:@"Person" inManagedObjectContext:cxt];
 6     NSFetchRequest * request = [[NSFetchRequest alloc] init];
 7     [request setEntity:entityDescription];
 8
 9     NSSortDescriptor * sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES];
10     [request setSortDescriptors:@[sortDescriptor]];
11
12     NSError * error = nil;
13     NSArray * listData = [cxt executeFetchRequest:request error:&error];
14     NSMutableArray * resListArray = [[NSMutableArray alloc] init];
15
16     for (Person * handle in listData) {
17         Person * person = [[Person alloc] init];
18         person.name = handle.name;
19         person.age = handle.age;
20
21         [resListArray addObject:person];
22     }
23
24     return resListArray;
25 }