1.首先创建上下文 这里就不多复述了 详见 《CoreData 的简单使用__ 01》。
2.(1)我们先添加多条信息来方便我们的模糊查询操作，代码如下：
-(void)addEmployee{
for(inti =0; i <15; i++) {
Employee*emp = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:_context];
emp.name= [NSString stringWithFormat:@"jasoneIo%d",i];
emp.height=@(1.80+ i);
emp.birthday= [NSDate date];
}
//直接保存数据库
NSError*error =nil;
[_context save:&error];
if(error) {
NSLog(@"%@",error);
}
}
(2)模糊查询
-(void)readEmployee{
// 1.FectchRequest抓取请求对象
NSFetchRequest*request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"];
// 3.设置排序
//身高的升序排序
NSSortDescriptor*heigtSort = [NSSortDescriptor sortDescriptorWithKey:@"height"ascending:YES];
request.sortDescriptors=@[heigtSort];
//名字以"jasoneIo1"开头
NSPredicate*pre = [NSPredicate predicateWithFormat:@"name BEGINSWITH %@",@"jasoneIo1"];
request.predicate= pre;
//名字以"1"结尾
NSPredicate*pre = [NSPredicate predicateWithFormat:@"nameENDSWITH%@",@"1"];
request.predicate= pre;
//名字包含"eIo11"
NSPredicate*pre = [NSPredicate predicateWithFormat:@"name CONTAINS %@",@"eIo11"];
request.predicate= pre;
// like
NSPredicate*pre = [NSPredicate predicateWithFormat:@"name like %@",@"*eIo1*"];
request.predicate= pre;
// 4.执行请求
NSError*error =nil;
NSArray*emps = [_context executeFetchRequest:requesterror:&error];
if(error) {
NSLog(@"error");
}
//NSLog(@"%@",emps);
//遍历员工
for(Employee*emp in emps) {
NSLog(@"名字%@身高%@生日%@",emp.name,emp.height,emp.birthday);
}
(3) 分页查询
-(void)pageSeacher{
// 1.FectchRequest抓取请求对象
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"];
// 3.设置排序
//身高的升序排序
NSSortDescriptor *heigtSort = [NSSortDescriptor sortDescriptorWithKey:@"height"ascending:YES];
request.sortDescriptors=@[heigtSort];
//总有共有15数据
//每次获取6条数据
//第一页0,6
//第二页6,6
//第三页12,6 3条数据
//分页的起始索引
request.fetchOffset=12;
//分页的条数
request.fetchLimit=6;
// 4.执行请求
NSError*error =nil;
NSArray*emps = [_context executeFetchRequest:requesterror:&error];
if(error) {
NSLog(@"error");
}
//NSLog(@"%@",emps);
//遍历员工
for(Employee*emp in emps) {
NSLog(@"名字%@身高%@生日%@",emp.name,emp.height,emp.birthday);
}
}
