Swift 核心数据';s托管对象属性作为参数
any第一条语句不返回任何值,而第二条语句工作正常。是否可以将属性名指定为参数之一以避免硬编码Swift 核心数据';s托管对象属性作为参数,swift,core-data,nspredicate,Swift,Core Data,Nspredicate,any第一条语句不返回任何值,而第二条语句工作正常。是否可以将属性名指定为参数之一以避免硬编码 let predicate = NSPredicate(format: "%@ == %@", "id","553178666d61d70c24fe4221") let predicate = NSPredicate(format: "id == %@", "553178666d61d70c24fe4221") 这是一个完整的解决方案,多亏了@Free昵称 class func searchF
let predicate = NSPredicate(format: "%@ == %@", "id","553178666d61d70c24fe4221")
let predicate = NSPredicate(format: "id == %@", "553178666d61d70c24fe4221")
这是一个完整的解决方案,多亏了@Free昵称
class func searchForObject(propertyName:NSString,property:NSString,className:String,single:Bool )->AnyObject?{
let fetchRequest = NSFetchRequest(entityName: className)
let predicate = NSPredicate(format: "%K == %@", argumentArray: [propertyName, property])
var appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
fetchRequest.predicate = predicate
// Execute the fetch request, and cast the results to an array of LogItem objects
var error:NSError?
if let fetchResults = appDelegate.managedObjectContext!.executeFetchRequest(fetchRequest, error: &error) as [AnyObject]? {
if let e = error{
println(e.debugDescription)
}
if single {
var object: AnyObject? = fetchResults.first
return object;
}
else{
return fetchResults
}
}
return nil;
}
请尝试使用
%K
而不是%@
作为属性名称。
像这样:
资料来源:
从文档中:
格式字符串支持printf样式的格式说明符,如%x(请参阅格式化字符串对象)。两个重要的格式说明符是%@
和%K
是对对象值(通常是字符串、数字或日期)的var arg替换%@
是密钥路径的变量arg替换%K
let predicate = NSPredicate(format: "%K == %@", "id","553178666d61d70c24fe4221")