iphone - NSSortDescriptor 根本无法计算数字

有了这个

    NSSortDescriptor *lessonDescriptor = [[NSSortDescriptor alloc] initWithKey"lesson" ascending:YES];
[resultArray sortUsingDescriptors:[NSArray arrayWithObject:lessonDescriptor]];

它正在将“类(class)”对象排序为

(
    {
    lesson = 9;
    subject = bg;
},
    {
    lesson = 8;
    subject = bg;
},
    {
    lesson = 11;
    subject = CAE;
},
    {
    lesson = 11;
    subject = CAE;
},
    {
    lesson = 10;
    subject = CAE;
},
    {
    lesson = 10;
    subject = CAE;
},
    {
    lesson = 5;
    subject = Gg;
},
    {
    lesson = 4;
    subject = G;
},
    {
    lesson = 3;
    subject = G;
},
    {
    lesson = 2;
    subject = M;
},
    {
    lesson = 1;
    subject = M;
}

)

如您所见，它的计数不正确。有人可以帮忙吗？

非常感谢

编辑:

不知道怎么实现值的东西=)

else if ([currentElement isEqualToString"lesson"]) 
{ 

    NSString *trimmedString = [string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
    NSLog(@"trimmed: %@",trimmedString);
    int value = [trimmedString intValue];   ??
    [currentSummary appendString:value];  ??

    [currentSummary appendString:trimmedString]; 
} 

---

Best Answer-推荐答案

您必须在将“类(class)”转换为数字之前修剪字符串，以便排序描述符正常工作。否则，排序描述符只能看到字符串值而不是数字。这是删除空格和换行符的方法:

NSString *stringValue = [parsedValue stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

调用[stringValue intValue]会得到字符串的整数值

int value = [stringValue intValue];

在调用此属性的排序描述符之前将此值保存到数组中。

告诉我它是否有效。

关于iphone - NSSortDescriptor 根本无法计算数字，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/3949294/