iOS获取属性类 [英] iOS get property class

问题描述

我正在尝试获取未知类的所有属性列表以及每个属性的类。到目前为止，我得到了一个对象的所有属性的列表（我递归地获取所有的超类）。我启发了这篇文章

I'm trying to get a list of all the properties of an unknown class and the class of every property. By the moment I get a list of all the properties of an object(I do it recursively to get all of the superclasses). I inspired in this post

+ (NSArray *)classPropsFor:(Class)klass
{    
    NSLog(@"Properties for class:%@", klass);
    if (klass == NULL || klass == [NSObject class]) {
        return nil;
    }

    NSMutableArray *results = [[NSMutableArray alloc] init];

    unsigned int outCount, i;
    objc_property_t *properties = class_copyPropertyList(klass, &outCount);
    for (i = 0; i < outCount; i++) {
        objc_property_t property = properties[i];
        const char *propName = property_getName(property);
        if(propName) {
            NSString *propertyName = [NSString stringWithUTF8String:propName];
            [results addObject:propertyName];
        }
        NSArray* dict = [self classPropsFor:[klass superclass]];
        [results addObjectsFromArray:dict];
    }
    free(properties);

    return [NSArray arrayWithArray:results];
}

所以现在我想要每个属性的类，我这样做：

So now I want the class of every property and I do:

NSArray* properties = [PropertyUtil classPropsFor:[self class]];
for (NSString* property in properties) {
    id value= [self valueForKey:property];
    NSLog(@"Value class for key: %@ is %@", property, [value class]);
}

问题是它适用于NSStrings，但不适用于自定义类，它返回null。我想递归地创建一个字典来表示一个对象，里面可以有其他对象，因为我认为我需要知道每个属性的类，这可能吗？

The problem is it works for NSStrings or but not for custom classes, for that it returns me null. I want to recursively create a dictionary that represents an object that can have other objects inside and as I thinks I need to know the class of every property, is that possible?

推荐答案

您应该在存储 propertyName 的同时为每个属性存储类（作为字符串）。也许作为一个字典，其属性名称为键，类名称为值，反之亦然。

You should probably store the class (as a string) for each property at the same time as you store the propertyName. Maybe as a dictionary with property name as the key and class name as the value, or vice versa.

要获取类名，可以执行以下操作（put这是在你声明 propertyName ）之后：

To get the class name, you can do something like this (put this right after you declare propertyName):

NSString* propertyAttributes = [NSString stringWithUTF8String:property_getAttributes(property)];
NSArray* splitPropertyAttributes = [propertyAttributes componentsSeparatedByString:@"\""];
if ([splitPropertyAttributes count] >= 2)
{
    NSLog(@"Class of property: %@", [splitPropertyAttributes objectAtIndex:1]);
}

字符串处理代码是因为属性包含许多信息 - 具体细节在此处指定： https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/ocrtPropertyIntrospection.html

The string handling code is because the attributes include a number of pieces of information - the exact details are specified here: https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/ocrtPropertyIntrospection.html

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