Question

我尝试使用一对多关系将数据插入实体。我的实体名称为Student和Detail。 Student与Detail有多个关系，Detail到student有一种关系。关系名称为detailRelationship，从Student到Detail＆amp; studentRelationship从Detail到Student。

StudentCoreDataclassProperties

#import "Student+CoreDataClass.h"


NS_ASSUME_NONNULL_BEGIN

@interface Student (CoreDataProperties)

+ (NSFetchRequest<Student *> *)fetchRequest;

@property (nullable, nonatomic, copy) NSString *number;
@property (nullable, nonatomic, retain) NSSet<Detail *> *detailRelationship;

@end

@interface Student (CoreDataGeneratedAccessors)

- (void)addStudentRelationshipObject:(Detail *)value;
- (void)removeStudentRelationshipObject:(Detail *)value;
- (void)addStudentRelationship:(NSSet<Detail *> *)values;
- (void)removeStudentRelationship:(NSSet<Detail *> *)values;

@end

DetailCoreDataclassProperties

#import "Detail+CoreDataClass.h"


NS_ASSUME_NONNULL_BEGIN

@interface Detail (CoreDataProperties)

+ (NSFetchRequest<Detail *> *)fetchRequest;

@property (nullable, nonatomic, copy) NSString *name;
@property (nullable, nonatomic, copy) NSString *address;
@property (nullable, nonatomic, retain) Student *studentRelationship;
//@property (nullable, nonatomic, retain) NSSet<Detail *> *studentRelationship;

@end

@interface Detail (CoreDataGeneratedAccessors)

- (void)addDetailRelationshipObject:(Detail *)value;
- (void)removeDetailRelationshipObject:(Detail *)value;
- (void)addDetailRelationship:(NSSet<Detail *> *)values;
- (void)removeDetailRelationship:(NSSet<Detail *> *)values;

@end

插入数据的代码

- (IBAction)submit:(id)sender {
    AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
    _mainContext = [appDelegate manageObjectContext];

    Detail *detailtEntity = (Detail *)[NSEntityDescription insertNewObjectForEntityForName:@"Detail" inManagedObjectContext:_mainContext];
    _studentClass = (Student *)[NSEntityDescription insertNewObjectForEntityForName:@"Student" inManagedObjectContext:_mainContext];

    detailtEntity.name = _nameText.text;
    detailtEntity.address = _addressText.text;
    detailtEntity.address = _addressText1.text;
    detailtEntity.name = _nameText1.text;
    _studentClass.number = _numberText.text;
    NSMutableSet *mySet = [[NSMutableSet alloc] init];
    [mySet addObject: _studentClass];
    [detailtEntity addDetailRelationship:mySet];//crash app here
    detailtEntity.studentRelationship = _studentClass;

    NSError *error = nil;
    [_mainContext save:&error];

    if (![_mainContext save:&error]) {
        NSLog(@"error in adding data %@, %@", error, [error userInfo]);
        abort();
    }

    [self.navigationController popToRootViewControllerAnimated:YES];

}

告诉我这样的错误：＆＃39; NSInvalidArgumentException＆＃39;，原因：＆＃39; - [详细信息addDetailRelationship：]：发送到的无法识别的选择器实例0x6000000ad740＆＃39;

Answer 1

您正在发送带有签名的邮件

import matplotlib.pyplot as plt
import numpy as np

# Random test data
np.random.seed(123)
all_data = [np.random.normal(0, 5, 100) for std in range(1, 21)]

fig, ax = plt.subplots(nrows=1, figsize=(9, 4))

# rectangular box plot
bplot = ax.boxplot(all_data, 0, '', 0, patch_artist=True) 

cm = plt.cm.get_cmap('rainbow')
colors = [cm(val/len(all_data)) for val in range(len(all_data))]

for patch, color in zip(bplot['boxes'], colors):
    patch.set_facecolor(color)

plt.show()

但不存在具有该签名的方法。相反，你的签名是

- (void)addDetailRelationship:(NSSet<Student *> *)values,

（请注意从- (void)addDetailRelationship:(NSSet<Detail *> *)values到Detail *的更改。因此，您的应用会因无法识别的选择器异常而崩溃。我不知道您的程序逻辑是什么，但您需要要么使用此签名创建方法，要么传入正确类型的参数。

Answer 2

核心数据为您管理关系逆转。如果您设置了详细信息的学生关系，核心数据会自动将其设置为学生之一＆＃39;细节。没有任何需要崩溃的东西，所以只需删除

即可

    [detailtEntity addDetailRelationship:mySet];//crash app here

（它崩溃的原因是你需要在学生上添加详细的关系 - [_studentClass addDetailRelationship：mySet]。但正如我上面所说，你根本不需要这条线路。

原因：＆＃39; - [详细信息addDetailRelationship：]：无法识别的选择器发送到实例0x6000000ad740

2 个答案: