KVC

//属性相加

NSString *sum= [person valueForKeyPath:@"rePerson.@sum.age"];
NSLog(@"sum = %@",sum);
//数量
NSStrin
4000
g *count= [person valueForKeyPath:@"rePerson.@count.age"];
NSLog(@"count = %@",count);
//最大值
NSString *max= [person valueForKeyPath:@"rePerson.@max.age"];
NSLog(@"max = %@",max);
//最小值
NSString *min= [person valueForKeyPath:@"rePerson.@min.age"];
NSLog(@"min = %@",min);
//平均值
NSString *avg= [person valueForKeyPath:@"rePerson.@avg.age"];
NSLog(@"avg = %@",avg);

通常情况下在使用setValue:forKeyPath 时候 这个 setValue:forKeyPath  是放在最后的 在写 setValue:forKeyPath 之前要把前边的的属性都设置好了 之后在写 setValue:forKeyPath