[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：