如何通过firstName过滤NSMutableArray与非字母字符 [英] How can i filter NSMutableArray by firstName with non-alphabetical characters

问题描述

我想过滤数组，其中名称以非字母字符开头。我想在表视图中的不同部分下显示firstName以非字母字符开头的联系人。我尝试下面的代码，但它崩溃，请找到原因下面：

  NSPredicate * predicate = [NSPredicate predicateWithFormat：@NOT firstName BEGINSWITH [c]％@），arrIndex]; //其中arrIndex是字母字符数组。 
 NSArray * arrContacts = [arrayTotalContacts filteredArrayUsingPredicate：predicate]; 
 

由于未捕获异常而终止应用程序'NSInvalidArgumentException'，原因：'无法执行子字符串操作不是字符串的东西（lhs = iPhone rhs =（
A，
B，
C，
D，
E，
F，
G，
H，
I，
J，
K，
L，
M，
N，
O，
P，
Q，
R，
S，
T，
U，
V，
arrayTotalContacts具有以下数据：

 （
 {
 firstName = iPhone; 
 lastName =; 
} 
 {
 firstName = Madhu; 
 lastName =; 
}，
 {
 firstName =Swa; 
 lastName = ; 
}，
 {
 firstName = TechV; 
 lastName =; 
}，
 {
 firstName = Vedika; 
 lastName = Vt; 
} 
）
  

解决方案

您可以使用带有Core Data谓词的正则表达式：

  [NSPredicate predicateWithFormat：@NOT MATCHES％@），@^ [A-Za-z]。*] 
  

^ [A-Za-z]。* 是以AZ或az开头的所有字符串的正则表达式。
要使其与外语的字母（例如Ä）一起使用，请使用
Unicode属性名称：

  [NSPredicate predicateWithFormat：@NOT（firstName MATCHES％@），@^ \\p {Letter}。*] 
  

这里 ^ \\p {Letter}。* 是一个正则表达式，字母。

但如果这是一个表视图，你最好使用一个获取结果控制器
和它的 sectionNameKeyPath 参数。请参见此处：

• NSFetchedResultsController与字符串的第一个字母创建的部分

一些示例如何根据首字母分组表视图。应该是
可能修改代码以将不以字母开头的所有名称分组到
单独的组。

I want to filter the Array, where name starts with non-alphabetical characters. I want to display the contacts where firstName starts with non-alphabetical characters under different section in table view. I tried below code, but it crashing , please find reason below:

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"NOT(firstName BEGINSWITH[c] %@)",arrIndex]; //where arrIndex is the array of alphabetical characeters.
  NSArray  *arrContacts = [arrayTotalContacts filteredArrayUsingPredicate:predicate];

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Can't do a substring operation with something that isn't a string (lhs = iPhone rhs = ( A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z ))'

arrayTotalContacts has the below data:

(
{
    firstName = iPhone;
    lastName = "";
},
{
    firstName = Madhu;
    lastName = "";
},
{
    firstName = "Swa";
    lastName = "";
},
{
    firstName = TechV;
    lastName = "";
},
{
    firstName = Vedika;
    lastName = Vt;
}
)

解决方案

You can use regular expression with a Core Data predicate:

[NSPredicate predicateWithFormat:@"NOT (firstName MATCHES %@)", @"^[A-Za-z].*"]

where ^[A-Za-z].* is a regex for all strings that do start with A-Z or a-z. To make it work with letters from foreign languages as well (e.g. "Ä"), use the Unicode property name:

[NSPredicate predicateWithFormat:@"NOT(firstName MATCHES %@)", @"^\\p{Letter}.*"]

Here ^\\p{Letter}.* is a regex for all strings that start with a letter.

But if this is for a table view, you might better use a fetched results controller and its sectionNameKeyPath parameter. See for example here:

• NSFetchedResultsController with sections created by first letter of a string

for some examples how to group a table view according to the initial letter. It should be possible to modify the code to group all names that do not start with a letter into a separate group.

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