'NSInvalidArgumentException'，原因：'keypath Patient.nachname not found in entity <NSSQLEntity Patient id=1>'答案

【问题标题】：'NSInvalidArgumentException', reason: 'keypath Patient.nachname not found in entity <NSSQLEntity Patient id=1>''NSInvalidArgumentException'，原因：'keypath Patient.nachname not found in entity <NSSQLEntity Patient id=1>'
【发布时间】：2014-01-27 22:17:32
【问题描述】：

为什么我会收到 NSInvalidArgumentException？

我的表格视图控制器代码：

- (NSFetchedResultsController *)fetchedResultsController {

CoreDataHelper *cdh = [(MRMedSafeAppDelegate *) [[UIApplication sharedApplication] delegate] cdh];

if (_fetchedResultsController != nil) {
    return _fetchedResultsController;
}

NSFetchRequest  *fetchRequest = [[NSFetchRequest  alloc] init];
NSEntityDescription  *entity = [NSEntityDescription
                                entityForName:@"Patient" inManagedObjectContext:cdh.context];
[fetchRequest setEntity:entity];

NSSortDescriptor  *sort1 = [[NSSortDescriptor  alloc]
                            initWithKey:@"Patient.nachname" ascending:YES];
NSSortDescriptor  *sort2 = [[NSSortDescriptor  alloc]
                            initWithKey:@"Patient.vorname" ascending:YES];

[fetchRequest setSortDescriptors:[NSArray  arrayWithObjects:sort1, sort2, nil]];

[fetchRequest setFetchBatchSize:20];

NSFetchedResultsController *theFetchedResultsController =
[[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest
                                    managedObjectContext:cdh.context
                                      sectionNameKeyPath:nil
                                               cacheName:nil];
self.fetchedResultsController = theFetchedResultsController;
_fetchedResultsController.delegate = self;

return _fetchedResultsController;

}

我的病人.h：

@interface Patient : NSManagedObject
@property (nonatomic, retain) NSDate * geburtsdatum;
@property (nonatomic, retain) NSString * nachname;
@property (nonatomic, retain) NSString * vorname;
@property (nonatomic, retain) NSNumber * weiblich;
@end

我的病人.m：

#import "Patient.h"
@implementation Patient
@dynamic geburtsdatum;
@dynamic nachname;
@dynamic vorname;
@dynamic weiblich;
@end

XCode 5 从 Model.xcdatamodeld 文件中生成的 Patient.h 和 Patient.h。

为什么我会遇到异常？

* 由于未捕获的异常“NSInvalidArgumentException”而终止应用程序，原因：“keypath Patient.nachname not found in entity”

Patient 是唯一的类，模型中没有其他模型类，也没有关系。

【问题讨论】：

标签： ios core-data nsfetchedresultscontroller

【解决方案1】：

在

中使用“nachname”而不是“Patient.nachname”

NSSortDescriptor  *sort1 = [[NSSortDescriptor  alloc]
                        initWithKey:@"Patient.nachname" ascending:YES];

即它应该是

NSSortDescriptor  *sort1 = [[NSSortDescriptor  alloc]
                        initWithKey:@"nachname" ascending:YES];

下一个排序描述符和“vorname”也是如此。

【讨论】：