object-c runtime使用

最近在学习ios开发，尝试做个通讯录，使用了APAdress来读取系统的通信录，然后需要将通信录中的联系人转换为拼音并进行排序，最先想到的做法是取出APContact中的联系人名称，然后对这个名称进行排序，但这样做的话会导致整个排序代码职能给APContact用，如何使的这个排序代码可以给所有的类的用（此类中需要有特定的属性）,这时可以用到object-c的运行时特性

+(BOOL)ContainFullName:(Class)c
{
    static NSMutableDictionary *fullNameDict = nil;
    if(fullNameDict == nil)
    {
        fullNameDict = [NSMutableDictionary dictionary];
    }
    NSString *className = @(object_getClassName(c));
    NSString *fullName = fullNameDict[className];
    if(fullName == nil)
    {
        unsigned int nCount = 0;
        Ivar *ivars = class_copyIvarList(c, &nCount);
        for(int i = 0; i < nCount; i++)
        {
            Ivar ivar = ivars[i];
            NSString *varName = @(ivar_getName(ivar));
            if([varName hasPrefix:@"_"])
            {
                varName = [varName stringByReplacingCharactersInRange:NSMakeRange(0, 1) withString:@""];
            }
            if([varName isEqualToString:FULL_NAME])
            {
                fullNameDict[className] = varName;
                free(ivars);
                return YES;
            }
        }
        free(ivars);
        return NO;
    }
    else
    {
        return YES;
    }
    
}

通过ivar来查看是否有特定的属性，如果有，便获取该特性属性的值，并进行转换为拼音，然后将转换后的拼音和这个类关联并排序

+(NSArray*)letterSortedArray:(NSArray*)array
{
    NSArray *sortedArray = [NSMutableArray array];
    [array enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
        if([FullNameString ContainFullName:[obj class]])
        {
            NSString *name = [obj valueForKey:FULL_NAME];
            NSString *pinYinResult=[NSString string];
            NSString *regex = @"[A-Za-z]+";
            NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",regex];
            if ([predicate evaluateWithObject:name])
            {
                pinYinResult = [name capitalizedString];
            }
            else
            {
                for(int j=0;j<name.length;j++)
                {
                    char character = pinyinFirstLetter([name characterAtIndex:j]);
                    NSString *singlePinyinLetter=[[NSString stringWithFormat:@"%c",character]uppercaseString];
                    pinYinResult=[pinYinResult stringByAppendingString:singlePinyinLetter];
                }
            }
            
            objc_setAssociatedObject(obj, &pinyinKey, pinYinResult, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
        }
    }];
    
    array = [array sortedArrayUsingFunction:sortByID context:NULL];
    
    [array enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
        NSLog(@"name:%@", [obj valueForKey:FULL_NAME]);
    }];
    return sortedArray;
}

NSInteger sortByID(id obj1, id obj2, void *context)
{
    NSString *pinYinObj1 = objc_getAssociatedObject(obj1, &pinyinKey);
    NSString *pinYinObj2 = objc_getAssociatedObject(obj2, &pinyinKey);
   
    return [pinYinObj1 compare:pinYinObj2];
}