运行时候获得属性的名称

gistfile1.m

- (NSString *) nameWithInstance:(id)instance
{
    unsigned int numIvars = 0;
    NSString *key=nil;
    Ivar * ivars = class_copyIvarList([self class], &numIvars);
    for(int i = 0; i < numIvars; i++) {
        Ivar thisIvar = ivars[i];
        const char *type = ivar_getTypeEncoding(thisIvar);
        NSString *stringType =  [NSString stringWithCString:type encoding:NSUTF8StringEncoding];
        if (![stringType hasPrefix:@"@"]) {
            continue;
        }
        if ((object_getIvar(self, thisIvar) == instance)) {
            key = [NSString stringWithUTF8String:ivar_getName(thisIvar)];
            break;
        }
    }
    free(ivars);
    return key;
}