IOS数组排序

#pragma mark 数组排序4-高级排序
void arraySort4() {
Student *stu1 = [Student studentWithFirstname:@"MingJie" lastname:@"Li" bookName:@"book1"];
Student *stu2 = [Student studentWithFirstname:@"LongHu" lastname:@"Huang" bookName:@"book2"];
Student *stu3 = [Student studentWithFirstname:@"LianJie" lastname:@"Li" bookName:@"book2"];
Student *stu4 = [Student studentWithFirstname:@"Jian" lastname:@"Xiao" bookName:@"book1"];
NSArray *array = [NSArray arrayWithObjects:stu1,stu2,stu3, stu4, nil nil];
// 1.先按照书名进行排序
// 这里的key写的是@property的名称
NSSortDescriptor *bookNameDesc = [NSSortDescriptor sortDescriptorWithKey:@"book.name" ascending:YES];
// 2.再按照姓进行排序
NSSortDescriptor *lastnameDesc = [NSSortDescriptor sortDescriptorWithKey:@"lastname" ascending:YES];
// 3.再按照名进行排序
NSSortDescriptor *firstnameDesc = [NSSortDescriptor sortDescriptorWithKey:@"firstname" ascending:YES];
// 按顺序添加排序描述器
NSArray *descs = [NSArray arrayWithObjects:bookNameDesc, lastnameDesc, firstnameDesc, nil nil];
NSArray *array2 = [array sortedArrayUsingDescriptors:descs];
NSLog(@"array2:%@", array2);
}