[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：