[数据存储之七]CoreData操作练习

算是第一个功能全面些的例子吧，实现了利用CoreData的添加，删除，修改，查询的操作。

功能简单，CoreData提供的东西也没仔细看。关键代码贴上：

添加和修改代码：

NSData* iconData = UIImageJPEGRepresentation(_ImgViewCurrent.image, 1.0);
if (self.OpenViewModal == vmAddNew) {
NSManagedObject* Record = [NSEntityDescription insertNewObjectForEntityForName:@"Students"
inManagedObjectContext:_DBContext];
[Record setValue:_TextFiledName.text forKey:cdbName];
[Record setValue:_TextFiledPhone.text forKey:cdbTelephone];
[Record setValue:[NSNumber numberWithBool:_SwitchSex.on] forKey:cdbSex];
[Record setValue:iconData forKey:cdbIcon];
}
else{
[self.EditReord setValue:_TextFiledName.text forKey:cdbName];
[self.EditReord setValue:_TextFiledName.text forKey:cdbName];
[self.EditReord setValue:_TextFiledPhone.text forKey:cdbTelephone];
[self.EditReord setValue:[NSNumber numberWithBool:_SwitchSex.on] forKey:cdbSex];
[self.EditReord setValue:iconData forKey:cdbIcon];
}
[_DBContext save:nil];
[PublicFuns ShowMsg:@"保存完成!"];
[self.navigationController popViewControllerAnimated:YES];

查询代码：

-(void)RefreshData
{
AppDelegate* delegate = [UIApplication sharedApplication].delegate;
NSManagedObjectContext* _context = delegate.managedObjectContext;
NSFetchRequest* Requst = [[NSFetchRequest alloc] initWithEntityName:@"Students"];
NSEntityDescription* Entity = [NSEntityDescription entityForName:@"Students"
inManagedObjectContext:_context];
[Requst setEntity:Entity];
_FethchsObjects = [NSMutableArray arrayWithArray:[_context executeFetchRequest:Requst error:nil]];
[self.tableView reloadData];
}

NSManagedObject* Record = _FethchsObjects[indexPath.row];
UITableViewCell* Cell = nil;
if ([[Record valueForKey:cdbSex] boolValue]) {
Cell = [tableView dequeueReusableCellWithIdentifier:@"man"];
}
else {
Cell = [tableView dequeueReusableCellWithIdentifier:@"woman"];
}
[Cell setAccessoryType:UITableViewCellAccessoryDisclosureIndicator];
_DoubleGesture=[[UITapGestureRecognizer alloc] initWithTarget:self
action:@selector(EditStudent)];
[_DoubleGesture setNumberOfTapsRequired:2];
[Cell addGestureRecognizer:_DoubleGesture];
UIImageView* ImgView = (UIImageView*)[Cell viewWithTag:1];
UILabel* LabName = (UILabel*)[Cell viewWithTag:2];
UILabel* LabPhone = (UILabel*)[Cell viewWithTag:3];
NSData* iconData = (NSData*)[Record valueForKey:cdbIcon];
ImgView.image = [UIImage imageWithData:iconData];
LabName.text = [Record valueForKey:cdbName];
LabPhone.text = [Record valueForKey:cdbTelephone];
return Cell;

删除代码：

-(void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
NSInteger row = [indexPath row];
if (editingStyle == UITableViewCellEditingStyleDelete) {
AppDelegate* delegate = [UIApplication sharedApplication].delegate;
NSManagedObjectContext* _context = delegate.managedObjectContext;
[_context deleteObject:_CurrentObject];
[_FethchsObjects removeObject:_CurrentObject];
[_context save:nil];
NSArray* DelArr = [NSArray arrayWithObject:[NSIndexPath indexPathForRow:row inSection:0]];
[tableView deleteRowsAtIndexPaths:DelArr
withRowAnimation:UITableViewRowAnimationBottom];
[PublicFuns ShowMsg:@"删除完成!"];
}
}

总结下吧：

1，实现了利用CoreData，存储数据，例子中包括字符串,BOOL,二进制类型的数据。

2，操练了利用stroyBoard实现水平等分的方法，这个开始研究的时候，挺费时间的。

3，利用了oc的performSelector:WithObject的概念，给对象发送消息，降低耦合。但arc环境处理费点儿事，下面是两种处理方式。

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
id EditController = segue.destinationViewController;

/*大师级写法啊～*/
SEL SelModal = NSSelectorFromString(@"setOpenViewModal:");
IMP impModal = [EditController methodForSelector:SelModal];
void(*FuncModal)(id,SEL,NSInteger) = (void*) impModal;
FuncModal(EditController,SelModal,[sender integerValue]);

/*SEL SelRecord = NSSelectorFromString(@"setEditReord:");
IMP impRcord = [EditController methodForSelector:SelRecord];
void(*FuncRecord)(id,SEL,id) = (void*) impRcord;
FuncRecord(EditController,SelModal,_CurrentObject);*/
/*推荐方式啊，一劳永逸～*/
SuppressPerformSelectorLeakWarning
(
SEL SelRecord = NSSelectorFromString(@"setEditReord:");
[EditController performSelector:SelRecord withObject:_CurrentObject];
);

}

宏的原型：

#define SuppressPerformSelectorLeakWarning(Stuff) \
do { \
_Pragma("clang diagnostic push") \
_Pragma("clang diagnostic ignored \"-Warc-performSelector-leaks\"") \
Stuff; \
_Pragma("clang diagnostic pop") \
} while (0)

上个图吧：