如何更改NSSet对象的日期

Question

我有这个核心数据模型。我有一个学生，学生有父母（NSSet父母），父母有一些属性，也有属性addressHome和addressEmployer（地址也是对象所以他们有两个简单的对象 - addressHome和addressEmployer - 不是NSSet）。现在，我需要改变父母。我使用此代码更改父项属性，但工作非常奇怪。有时只保存母亲和父亲的一般数据，有时也是母亲的两个地址，但绝不是父亲的任何地址。我不理解它...我尝试调试，textFields填充正确，所以没有问题。你能告诉我吗？这是添加新学生的简单代码。

// add new student
if(!self.selectedStudentID){
    Student *student = [NSEntityDescription insertNewObjectForEntityForName:@"Student" inManagedObjectContext:cdh.context];

    // student hasnt parents --> create new
    if(student.parents.count == 0){
        Parent *mother = [NSEntityDescription insertNewObjectForEntityForName:@"Parent" inManagedObjectContext:cdh.context];
        mother.type = @"mother";
        [student addParentsObject:mother];

        Parent *father = [NSEntityDescription insertNewObjectForEntityForName:@"Parent" inManagedObjectContext:cdh.context];
        father.type = @"father";
        [student addParentsObject:father];
    }


    for (Parent *parent in student.parents) {
        // mother
        if([parent.type isEqualToString:@"mother"]){

            parent.name = motherVC.motherNameTextField.text;
            parent.job = motherVC.motherJobTextField.text;
            parent.phone = motherVC.motherPhoneHomeTextView.text;
            parent.phoneWork = motherVC.motherPhoneWorkTextView.text;

            // creating an AddressHome
            if(!parent.addressHome){
                Address *addressMotherHome = [NSEntityDescription insertNewObjectForEntityForName:@"Address" inManagedObjectContext:cdh.context];
                parent.addressHome = addressMotherHome;
            }

            // assign values
            parent.addressHome.city = motherVC.motherAddressCityTextField.text;
            parent.addressHome.street = motherVC.motherAddressStreetTextField.text;
            parent.addressHome.postcode = motherVC.motherAddressPostCodeTextField.text;
            parent.addressHome.houseNumber = motherVC.motherAddressHouseNumberTextField.text;

            // Creating an AddressEmployer
            if(!parent.addressEmployer){
                Address *addressMotherEmployer = [NSEntityDescription insertNewObjectForEntityForName:@"Address" inManagedObjectContext:cdh.context];
                parent.addressEmployer = addressMotherEmployer;
            }

            // assign values
            parent.addressEmployer.city = motherVC.motherEmployerAddressCityTextField.text;
            parent.addressEmployer.street = motherVC.motherEmployerAddressStreetTextField.text;
            parent.addressEmployer.postcode = motherVC.motherEmployerAddressPostCodeTextField.text;
            parent.addressEmployer.houseNumber = motherVC.motherEmployerAddressHouseNumberTextField.text;

            [cdh saveContext];
        }

        // father
        else if([parent.type isEqualToString:@"father"]){

            parent.name = fatherVC.fatherNameTextField.text;
            parent.job = fatherVC.fatherJobTextField.text;
            parent.phone = fatherVC.fatherPhoneHomeTextView.text;
            parent.phoneWork = fatherVC.fatherPhoneWorkTextView.text;

            // creating addressHome
            if(!parent.addressHome){
                Address *addressFatherHome = [NSEntityDescription insertNewObjectForEntityForName:@"Address" inManagedObjectContext:cdh.context];
                parent.addressHome = addressFatherHome;
            }

            // assign values
            parent.addressHome.city = fatherVC.fatherAddressCityTextField.text;
            parent.addressHome.street = fatherVC.fatherAddressStreetTextField.text;
            parent.addressHome.postcode = fatherVC.fatherAddressPostCodeTextField.text;
            parent.addressHome.houseNumber = fatherVC.fatherAddressHouseNumberTextField.text;

            // creating address-employer
            if(!parent.addressEmployer){
                Address *addressFatherEmployer = [NSEntityDescription insertNewObjectForEntityForName:@"Address" inManagedObjectContext:cdh.context];
                parent.addressEmployer = addressFatherEmployer;
            }

            // assign values
            parent.addressEmployer.city = fatherVC.fatherEmployerAddressCityTextField.text;
            parent.addressEmployer.street = fatherVC.fatherEmployerAddressStreetTextField.text;
            parent.addressEmployer.postcode = fatherVC.fatherEmployerAddressPostCodeTextField.text;
            parent.addressEmployer.houseNumber = fatherVC.fatherEmployerAddressHouseNumberTextField.text;

            [cdh saveContext];
        }
    }

    // assign values for student
    student.name = studentVC.studentNameTextField.text;
    student.birthNumber = studentVC.studentBirthNumberTextField.text;
    student.birthplace = studentVC.studentBirthPlaceTextField.text;
    student.identityCard = studentVC.studentIdentityCardTextField.text;
    student.nationality = studentVC.studentNationalityTextField.text;
    student.legalRepresentative = studentVC.studentLegalRepresentativeTextField.text;
    student.entranceToSchool = studentVC.studentEntranceToSchoolTextField.text;
    student.otherSchool = studentVC.studentOtherSchoolTextField.text;
    student.phone = studentVC.studentPhoneTextField.text;
    student.email = studentVC.studentEmailTextField.text;
    student.healthInsurer = studentVC.studentHealthInsurerTextField.text;
    student.codeOfHealthInsurer = studentVC.studentCodeOfHealthInsurerTextField.text;
    student.healthProblem = studentVC.studentHealthProblemTextView.text;
    student.releaseFromGym = studentVC.studentReleaseFromGymTextView.text;

    [cdh saveContext];

    // end of new student
}