objective-c - 根据 double 值对包含对象的 NSmutable 数组进行排序

Question

我想根据两个对象属性来排序 NSMutableArray 包含对象，其中一个具有 double 类型，第二个具有 NSString ？

我尝试使用此方法，但出现异常:

NSString * LASTNAME = @"lastName";
NSString * GRADE = @"grade";

NSSortDescriptor *lastDescriptor =
    [[NSSortDescriptor alloc]
        initWithKey:LASTNAME
          ascending:YES
           selector:@selector(localizedCaseInsensitiveCompare:)];

NSSortDescriptor *firstDescriptor =
    [[NSSortDescriptor alloc]
        initWithKey:GRADE
          ascending:YES
           selector:@selector(localizedCaseInsensitiveCompare:)]];

NSArray * descriptors =
   [NSArray arrayWithObjects:lastDescriptor, firstDescriptor, nil];
NSArray * sortedArray =
   [students sortedArrayUsingDescriptors:descriptors];

@interface Student : NSObject
{
    NSString * firstName;
    NSString * lastName;
    double grade;
}

Answer 1

NSNumber 不响应 localizedCaseInsensitiveCompare:。您只需要简单的 compare: 作为数字。