有没有办法在Cocoa/Cocoa Touch中动态确定运行时类的i​​vars？

Question

有没有办法获得像类的所有键值对的字典？

Answer 1

你必须使用Objective-C Runtime函数自己动手.这是一些非常基本的示例代码.请注意,获取类的ivars不会获得其超类的ivars.您需要明确地执行此操作,但函数都在运行时中.

#import <objc/objc-runtime.h>
#include <inttypes.h>
#include <Foundation/Foundation.h>

@interface Foo : NSObject
{
    int i1;
}
@end
@implementation Foo
@end

@interface Bar : Foo
{
    NSString* s1;
}

@end
@implementation Bar
@end

int main(int argc, char** argv)
{
    NSAutoreleasePool* pool = [[NSAutoreleasePool alloc] init];

    unsigned int count;
    Ivar* ivars = class_copyIvarList([Bar class], &count);
    for(unsigned int i = 0; i < count; ++i)
    {
        NSLog(@"%@::%s", [Bar class], ivar_getName(ivars[i]));
    }
    free(ivars);


    [pool release];
}

Answer 2

我不确定只有ivars但是如果你将它们定义为属性,则可以访问类的可用属性.

我一直在为几个项目使用SQLitePersistentObjects,它有一些有用的代码,可以获取在类中定义的属性,以便在与sqlite进行序列化时使用.

它使用函数class_copyPropertyList来获取类的可用属性列表.

进一步来说:

+(NSDictionary *)propertiesWithEncodedTypes
{

    // DO NOT use a static variable to cache this, it will cause problem with subclasses of classes that are subclasses of SQLitePersistentObject

    // Recurse up the classes, but stop at NSObject. Each class only reports its own properties, not those inherited from its superclass
    NSMutableDictionary *theProps;

    if ([self superclass] != [NSObject class])
        theProps = (NSMutableDictionary *)[[self superclass] propertiesWithEncodedTypes];
    else
        theProps = [NSMutableDictionary dictionary];

    unsigned int outCount;


    objc_property_t *propList = class_copyPropertyList([self class], &outCount);
    int i;

    // Loop through properties and add declarations for the create
    for (i=0; i < outCount; i++)
    {
        objc_property_t * oneProp = propList + i;
        NSString *propName = [NSString stringWithUTF8String:property_getName(*oneProp)];
        NSString *attrs = [NSString stringWithUTF8String: property_getAttributes(*oneProp)];
        NSArray *attrParts = [attrs componentsSeparatedByString:@","];
        if (attrParts != nil)
        {
            if ([attrParts count] > 0)
            {
                NSString *propType = [[attrParts objectAtIndex:0] substringFromIndex:1];
                [theProps setObject:propType forKey:propName];
            }
        }
    }

  free(propList);

    return theProps;    
}

这将返回属性的字典 - 您需要对您获得的结果进行一些调查,但如果您使用属性,则应该能够获得所需的内容.