Swift - 动态生成 NSPredicate？

Question

我正在尝试动态创建谓词并执行提取。

值可以是 String 或 Int，当和 int 值被发送到 NSPredicate 初始化程序时，它会崩溃并出现以下错误:

-[__NSCFNumber rangeOfString:]: 无法识别的选择器发送到实例

我知道问题是 Int 的 %@ 格式，但有没有办法让它动态化，这样我就不必手动检查 String 和 Int，然后创建谓词？

var keyValues: [String: AnyObject]
var predicates: [NSPredicate]()

for (key, value) in keyValues {
   var predicate = NSPredicate(format: "%K = %@", key: [value])
   predicates.append(predicate) 
}

var compundPredicate = NSCompoundPredicate.andPredicateWithSubpredicates(predicates)

Answer 1

value as NSObject 的作用:

var keyValues: [String: AnyObject] = ["name" : "John Doe", "age" : 39]
var predicates = [NSPredicate]()

for (key, value) in keyValues {
    var predicate = NSPredicate(format: "%K = %@", key, value as NSObject)
    predicates.append(predicate) 
}

var compundPredicate = NSCompoundPredicate.andPredicateWithSubpredicates(predicates)
println(compundPredicate)

输出:

name == "John Doe" AND age == 39

---

Update for Swift 3/4:

let keyValues = ["name" : "John Doe" as NSObject, "age" : 39 as NSObject]
var predicates = [NSPredicate]()

for (key, value) in keyValues {
    let predicate = NSPredicate(format: "%K = %@", key, value)
    predicates.append(predicate)
}

let compundPredicate = NSCompoundPredicate(andPredicateWithSubpredicates: predicates)

或更短:

let keyValues = ["name" : "John Doe" as NSObject, "age" : 39 as NSObject]
let predicates = keyValues.map { NSPredicate(format: "%K = %@", $0.key, $0.value) }
let compundPredicate = NSCompoundPredicate(andPredicateWithSubpredicates: predicates)