Swift NSPredicate在复合语句时抛出EXC_BAD_ACCESS（Code = 1，address = 0x1）

Question

我正在尝试在Swift中使用NSPredicate来查询核心数据，但是在尝试运行它时抛出EXC_BAD_ACCESS（Code = 1，address =
0x1）错误，我在做什么错？

这是发生错误的文件

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"
  }
}

Answer 1

%@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为NSNumber：

fetchRequest.predicate = NSPredicate(format: "level = %@", NSNumber(integer: level))

或改用ld格式化（长）整数：

fetchRequest.predicate = NSPredicate(format: "level = %ld", level)

另请注意

fetchRequest.predicate = NSPredicate(format: ...)
fetchRequest.predicate = NSPredicate(format: ...)

并 没有 创建复合谓词，使秒针分配简单地覆盖第一。您可以使用NSCompoundPredicate：

let p1 = NSPredicate(format: "level = %ld", level)!
let p2 = NSPredicate(format: "section = %ld", section)!
fetchRequest.predicate = NSCompoundPredicate.andPredicateWithSubpredicates([p1, p2])

或简单地将谓词与“ AND”组合：

fetchRequest.predicate = NSPredicate(format: "level = %ld AND section = %ld", level, section)