Swift NSPredicate在复合语句时抛出EXC_BAD_ACCESS（Code = 1，address = 0x1） [英] Swift NSPredicate throwing EXC_BAD_ACCESS(Code=1, address=0x1) when compounding statements

问题描述

我试图在Swift中使用NSPredicate来查询核心数据，但它尝试运行它时抛出一个EXC_BAD_ACCESS（Code = 1，address = 0x1）错误，我做错了什么？

这里是错误发生的文件

  class LevelsScreenModel：UIViewController {
 
 func getWord（level：Int，section：Int） - > String 
 {
 let fetchRequest = NSFetchRequest（entityName：Words）
 
 //这是发生错误的行
 fetchRequest.predicate = NSPredicate ：level =％@，level）
 fetchRequest.predicate = NSPredicate（format：section =％@，section）
 
 let word = AppDelegate（）。managedObjectContext！.executeFetchRequest （fetchRequest，error：nil）as [Words] 
 
 if（word.count> 1）
 {
 for word in 
 {
 println（words.word）
 return words.word 
} 
} 
 
 returnERROR
} 
} 
   
 
解决方案
 ％@ 谓词格式字符串中的占位符用于Objective-C 
对象，因此您必须将整数包装到 NSNumber ：
  fetchRequest.predicate = NSPredicate（format：level =％@，NSNumber（integer：level））
  pre> 
 
 
或使用 ld 代替格式化一个（长整数）：
  fetchRequest.predicate = NSPredicate（format：level =％ld，level）
   
 
注意
  fetchRequest.predicate = NSPredicate（format：...） 
 fetchRequest.predicate = NSPredicate（format：...）
  
 创建复合谓词，秒分配只需
覆盖第一个。您可以使用 NSCompoundPredicate ：
  let p1 = NSPredicate level =％ld，level）！ 
 let p2 = NSPredicate（format：section =％ld，section）！ 
 fetchRequest.predicate = NSCompoundPredicate.andPredicateWithSubpredicates（[p1，p2]）
  
 AND的谓词：
  fetchRequest.predicate = NSPredicate（format：level =％ld AND section =％ld ，level，section）
  
 
I am trying to use NSPredicate in Swift to query Core Data but it throws an EXC_BAD_ACCESS(Code=1, address=0x1) error when trying to run it, what am I doing wrong?

Here is the file where the error happens
class LevelsScreenModel : UIViewController {

func getWord(level: Int, section: Int) -> String
{
    let fetchRequest = NSFetchRequest(entityName: "Words")

    //This is the line where the error happens
    fetchRequest.predicate = NSPredicate(format: "level = %@", level)
    fetchRequest.predicate = NSPredicate(format: "section = %@", section)

    let word = AppDelegate().managedObjectContext!.executeFetchRequest(fetchRequest, error: nil) as [Words]

    if(word.count > 1)
    {
        for words in word
        {
            println(words.word)
            return words.word
        }
    }

    return "ERROR"
  }
}

解决方案
The %@ placeholder in predicate format strings is for Objective-C
objects, so you have to wrap the integer into an NSNumber:
fetchRequest.predicate = NSPredicate(format: "level = %@", NSNumber(integer: level))
or use ld instead to format a (long) integer:
fetchRequest.predicate = NSPredicate(format: "level = %ld", level)
Note also that 
fetchRequest.predicate = NSPredicate(format: ...)
fetchRequest.predicate = NSPredicate(format: ...)
does not create a compound predicate, the seconds assignment simply
overwrites the first. You can use an NSCompoundPredicate:
let p1 = NSPredicate(format: "level = %ld", level)!
let p2 = NSPredicate(format: "section = %ld", section)!
fetchRequest.predicate = NSCompoundPredicate.andPredicateWithSubpredicates([p1, p2])
or simply combine the predicates with "AND":
fetchRequest.predicate = NSPredicate(format: "level = %ld AND section = %ld", level, section)


                        
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