NSPredicate predicateWithFormat：argumentArray：仅评估第一个参数

问题描述

我有一些麻烦使用

的第一个值。我似乎不能得到谓词来评估整个数组。 
 
 
 
谢谢！
解决方案
 >  [NSPredicate predicateWithFormat：@（flid IN％@）argumentArray：serverIDList] 
  

等同于

  [NSPredicate predicateWithFormat：@（flid IN％@），id1，id2， 。，idN] 
  

其中 id1 ..， idN 是数组 serverIDList 的元素。
这应该解释为什么只有第一个元素被评估。

你可能想要的是

  [NSPredicate predicateWithFormat：@（flid IN％@），serverIDList] 
  

$ b b

备注：我建议不要先将谓词创建为字符串。
引用或转义错误的机会相当高。只能使用
常量格式字符串使用 predicateWithFormat 。如果你必须在运行时动态合并谓词，
使用 NSCompoundPredicate 。

I'm having some trouble using NSPredicate predicateWithFormat:argumentArray:. In this example, serverIDList is array of strings. Results is an array of NSManagedObjects with an attribute named "flid" which is a string.

NSMutableString *predicateString = [[NSMutableString alloc] init];

[predicateString appendString:@"(flid IN %@)"];

[results filterUsingPredicate:[NSPredicate predicateWithFormat:predicateString argumentArray:serverIDList]];

The problem is that [NSPredicate predicateWithFormat:predicateString argumentArray:serverIDList] evaluates to "flid IN '2155'", which is only the first value of the array serverIDList. I can't seem to get the predicate to evaluate the entire array. Is there something missing here?

Thanks!

解决方案

[NSPredicate predicateWithFormat:@"(flid IN %@)" argumentArray:serverIDList]

is equivalent to

[NSPredicate predicateWithFormat:@"(flid IN %@)", id1, id2, ..., idN]

where id1, ..., idN are the elements of the array serverIDList.That should explain why only the first element is evaluated.

What you probably want is

[NSPredicate predicateWithFormat:@"(flid IN %@)", serverIDList]

Remark: I would recomment not to create predicates as strings first. The chances forquoting or escaping errors are quite high. Use only predicateWithFormat with a constant format string. If you have to combine predicates dynamically at runtime,use NSCompoundPredicate.

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