NSMutableArray *commentListArray=[[NSMutableArray alloca]init];
// 为每个属性创建NSSortDescriptor对象,并确定为升序
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"commentId" ascending:YES];//
// 设置排序优先级，并组成数组。这里优先级最高为commentId
NSArray * sortDescriptors = [[NSArray alloc] initWithObjects:&sortDescriptor count:1];
[commentListArray sortUsingDescriptors:sortDescriptors];
// 为数组中每个元素执行方法，输出状态
[commentListArray makeObjectsPerformSelector:@selector(printState)];
