编辑和删除 NSMutablearray 中的元素

Question

我有一个 NSMutableArray，它的数据是字典格式的，例如：

(
        {
        subject = “Maths";
        rollNo = "#1";
        division = A;
    },
        {
        subject = “Science”;
        rollNo = “#2”;
        division = A;
    },
 {
        subject = “Maths";
        rollNo = “#3”;
        division = A;
    },
 {
        subject = “Maths";
        rollNo = “#4”;
        division = B;
    },
 {
        subject = “Science”;
        rollNo = “#5”;
        division = A;
    },
 {
        subject = “English”;
        rollNo = “#6”;
        division = A;
    },
)

现在我需要合并属于同一学科和部门的卷号并修改现有数组，如下所示

(
        {
        subject = “Maths";
        rollNo = “#1,#3”;
        division = A;
    },
        {
        subject = “Science”;
        rollNo = “#2,#5”;
        division = A;
    },

 {
        subject = “Maths";
        rollNo = “#4”;
        division = B;
    },

 {
        subject = “English”;
        rollNo = “#6”;
        division = A;
    },
)

This is how I'm trying to achieve it

 NSMutableArray *temp =[studentDetailsArray mutableCopy];
 NSMutableArray *elementToDelete = [NSMutableArray array];
 for (int m=0; m<temp.count-1; m++)
 {
 if ([temp[m][@"subject"] isEqualToString:temp[m+1][@"subject"]] && [temp[m][@“division”] isEqualToString:temp[m+1][@“division”]])
 {
 [temp[m] replaceObjectAtIndex:1 withObject:@{@"rollNo":[NSString stringWithFormat:@"%@, %@",temp[m][@"rollNo"],temp[m+1][@"rollNo"]]}];
 //                    [temp[m] setValue:[NSString stringWithFormat:@"%@, %@",temp[m][@"rollNo"],temp[m+1][@"rollNo"]]forKey:@"rollNo"];
 [elementToDelete addObject:temp[m+1]];
 }
 }

 [temp removeObjectsInArray:elementToDelete];

但是我在替换对象时遇到错误，所以我必须将它转换成 NSMutableDictionary 吗？我应该如何着手以简单的方式做到这一点？

Answer 1

不需要创建更多数组。你得到错误是因为这一行：

[temp[m] replaceObjectAtIndex:1 withObject:@{@"rollNo":[NSString stringWithFormat:@"%@, %@",temp[m][@"rollNo"],temp[m+1][@"rollNo"]]}];

应该是

NSMutableDictionary *mutable = [temp[m] mutableCopy];

[mutable setObject:[NSString stringWithFormat:@"%@, %@",temp[m][@"rollNo"],temp[m+1][@"rollNo"]] forKey:@"rollNo"];
[temp replaceObjectAtIndex:m withObject:mutable];

编辑和删除 NSMutablearray 中的元素

Edit and delete elements from an NSMutable array

objective-c

nsmutablearray

nsmutabledictionary

ios

ios7.1