Question

核心数据，NSManagedObject，

我从MacResearch.org获得名为Molecular Core的演示应用程序的源代码

有一个名为Molecule的类。它是NSManagedObject的子类。当我尝试在Molecule实例上调用实例方法时我在下面的NSLog消息后面得到一个'无法识别的选择器'错误消息：

2011-04-04 20：41：44.778 Molecular Core [13766：903] symbol = Ag molecule =（entity：Molecule; id：0x1230b70; data：{ atoms =（）; name =“New Molecule”; }） COORDS [1] = 2.500000

2011-04-04 20：41：45.917 Molecular Core [13766：903] - [NSManagedObject addAtomWithPosition：andSymbol：]：无法识别的选择器发送到实例0x1234d00

这是我的问题：

Molecule.h声明方法addAtomWithPosition：andSymbol：与Molecule.m中的定义完全相同。为什么系统无法找到此方法。 Molecule的例子似乎只被视为它的超类NSManagedObject的一个实例。那是为什么？

感谢阅读！标记

//
//  Molecule.h
//  Molecular Core
#import <Foundation/Foundation.h>
@class Atom;

@interface Molecule : NSManagedObject {
@private

}
@property (readwrite, copy) NSString *name;

/// THIS SELECTOR/METHOD IS 'INVISIBLE' TO COMPILER   //////

-(id)addAtomWithPosition:(double *)position andSymbol:(NSString *)symbol;

/// THIS CLASS METHOD IS VISIBLE TO COMPILER'   //////

+(id)moleculeFromXYZString:(NSString *)xyzString withName:(NSString *)name 
        inManagedObjectContext:(NSManagedObjectContext *)context;

@end
/// end molecule.h  /////////////////

// begin molecule.m  /////////////
//
//  Molecule.m

#import "Molecule.h"
#import "Atom.h"
#import "Element.h"

@implementation Molecule
@dynamic  name;


-(id)init
{
    self = [super init];
    if (self) {
        // Initialization code here.
    }

  return self;
}

    //// THIS CLASS METHOD RUNS     ////////////

    +(id)moleculeFromXYZString:(NSString *)xyzString 
       withName:(NSString *)name inManagedObjectContext:(NSManagedObjectContext *)context 
    {

   Molecule *molecule;

   molecule = (Molecule*) [NSEntityDescription insertNewObjectForEntityForName:@"Molecule" 
            inManagedObjectContext:context];

   molecule.name = name;

   NSScanner *scanner = [NSScanner scannerWithString:(nil == xyzString ? @"" : xyzString)];

   [scanner setCharactersToBeSkipped:[NSCharacterSet whitespaceCharacterSet]];

   BOOL xyzLine = NO;

   BOOL firstLineFound = NO;

   NSCharacterSet *newlineSet;

   newlineSet = [NSCharacterSet characterSetWithCharactersInString:@"\n"];

   while ( ![scanner isAtEnd] && ( ( xyzLine && firstLineFound ) || !firstLineFound ) ) 
    {

  NSString *line = nil;

  NSScanner *lineScanner;

  double coords[3];

  NSString *symbol;

  if ( ![scanner scanUpToCharactersFromSet:newlineSet intoString:&line] ) 
     line = @"";

  [scanner scanString:@"\n" intoString:NULL];

  lineScanner = [NSScanner scannerWithString:line]; // Create scanner for scanning line content

  [lineScanner setCharactersToBeSkipped:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

  xyzLine = [lineScanner scanCharactersFromSet:[NSCharacterSet letterCharacterSet] intoString:&symbol] &&
     [lineScanner scanDouble:&(coords[0])] && 
     [lineScanner scanDouble:&(coords[1])] && 
     [lineScanner scanDouble:&(coords[2])];

  NSLog(@"symbol=%@\nmolecule=%@\ncoords[1]=%f",symbol,molecule,(coords[1]));

  if ( xyzLine ) {

   firstLineFound = YES;

     //// THIS IS THE CALL THAT FAILS       /////////////////////

         [((Molecule*)molecule) addAtomWithPosition:(double *)coords andSymbol:(NSString*)symbol];
       }
     }

  return molecule;
  }

    -(id)addAtomWithPosition:(double *)position andSymbol:(NSString *)symbol {

       Atom *atom = [NSEntityDescription insertNewObjectForEntityForName:@"Atom" 
                                              inManagedObjectContext:[self managedObjectContext]];

       Element *element = [Element elementWithSymbol:symbol inManagedObjectContext:[self  managedObjectContext]];

       atom.molecule = self;

       atom.element = element;

       atom.positionX = [NSNumber numberWithDouble:position[0]];

       atom.positionY = [NSNumber numberWithDouble:position[1]];

       atom.positionZ = [NSNumber numberWithDouble:position[2]];

       NSLog(@"positionY=%@",atom.positionY);

       return atom;
    }


-(void)dealloc
{
  [super dealloc];
}

@end

Answer 1

NSManagedObject不会响应选择器，但Molecule的子类NSManagedObject会响应。您需要将实体Molecule的类设置为Core Data模型中的类Molecule。

除了在* .h文件中的界面中声明之外，如何使从NSManagedObject子类化的对象的选择器对编译器可见？

1 个答案: