无法从对象创建BOOL

Question

我正在跟随《Mac OS X下的Cocoa编程》第四版指南。在第32章中，我搞砸了代码，并且没有备份，所以我不得不从Big Nerd Ranch下载解决方案。
该项目涉及核心数据关系，有一个Employee类和一个Department类。

Employee.h:

#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>

@class Department;

@interface Employee : NSManagedObject

@property (nonatomic, copy) NSString * firstName;
@property (nonatomic, copy) NSString * lastName;
@property (nonatomic, retain) Department *department;
@property (nonatomic, readonly) NSString *fullName;

@end

Employee.m：

#import "Employee.h"
#import "Department.h"


@implementation Employee

@dynamic firstName;
@dynamic lastName;
@dynamic department;

+ (NSSet *)keyPathsForValuesAffectingFullName
{
    return [NSSet setWithObjects:@"firstName", @"lastName", nil];
}

- (NSString *)fullName
{
    NSString *first = [self firstName];
    NSString *last = [self lastName];
    if (!first)
        return last;
    if (!last)
        return first;
    return [NSString stringWithFormat:@"%@ %@", first, last];
}

@end

Department.h：

#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>


@interface Department : NSManagedObject

@property (nonatomic, retain) NSString * deptName;
@property (nonatomic, retain) NSSet *employees;
@property (nonatomic, retain) NSManagedObject *manager;
@end

@interface Department (CoreDataGeneratedAccessors)

- (void)addEmployeesObject:(NSManagedObject *)value;
- (void)removeEmployeesObject:(NSManagedObject *)value;
- (void)addEmployees:(NSSet *)values;
- (void)removeEmployees:(NSSet *)values;

@end

Department.m：

#import "Department.h"
#import "Employee.h"

@implementation Department

@dynamic deptName;
@dynamic employees;
@dynamic manager;

- (void)addEmployeesObject:(Employee *)value
{
    NSLog(@"Dept %@ adding employee %@",
          [self deptName], [value fullName]);
    NSSet *s = [NSSet setWithObject:value];
    [self willChangeValueForKey:@"employees"
                withSetMutation:NSKeyValueUnionSetMutation
                   usingObjects:s];
    [[self primitiveValueForKey:@"employees"] addObject:value];
    [self didChangeValueForKey:@"employees"
               withSetMutation:NSKeyValueUnionSetMutation
                  usingObjects:s];
}

- (void)removeEmployeesObject:(Employee *)value
{
    NSLog(@"Dept %@ removing employee %@",
          [self deptName], [value fullName]);
    Employee *manager = (Employee *)[self manager];
    if (manager == value) {
        [self setManager:nil];
    }
    NSSet *s = [NSSet setWithObject:value];
    [self willChangeValueForKey:@"employees"
                withSetMutation:NSKeyValueMinusSetMutation
                   usingObjects:s];
    [[self primitiveValueForKey:@"employees"] removeObject:value];
    [self didChangeValueForKey:@"employees"
               withSetMutation:NSKeyValueMinusSetMutation
                  usingObjects:s];
}


@end

我有这些核心数据关系和实体：

我也使用一些数组控制器将核心数据值绑定到某些输出口。
完整的项目可以在这里找到，第32章（与我的相同）在“下载解决方案”中。 如果您需要更多的代码来理解这个错误，请告诉我。

2012-10-31 15:27:43.977 Departments[1229:303] Cannot create BOOL from object (
) of class _NSControllerArrayProxy
2012-10-31 15:27:43.989 Departments[1229:303] Cannot create BOOL from object (
) of class _NSControllerArrayProxy

似乎不推荐发布整个项目，但如果您认为可以的话，我可以这样做。

附注：我正在使用从解决方案中下载的代码，它是相同的，但不起作用，可能是因为我有更高版本的Xcode。

- Ramy Al Zuhouri

Answer 1

看起来是绑定问题。你可能将一个无法转换为BOOL的属性与一个接受BOOL的“启用”或“隐藏”绑定相连。

- diederikh

---

我仍然找不到问题，唯一使用返回BOOL的方法连接的是数组控制器的canRemove方法。我该如何发布xib文件？ - Ramy Al Zuhouri

也许了解NSControllerArrayProxy对象通常是NSArrayController的contentArray会有所帮助。 - diederikh

以下是一些绑定：Depts数组控制器的托管对象上下文与文件所有者、模型关键路径managedObjectContext绑定。ManagerPopUp的内容集合与Depts选择的employees绑定。EmployeeList数组控制器的内容集合与Depts选择的employees绑定。 - Ramy Al Zuhouri

没什么事，一切都好了，我只需要进行一次干净的构建并删除派生数据中的项目文件夹。 - Ramy Al Zuhouri