Ios 用于定义NSPredicate的If else语句

我试图定义一个基于段控制器开关的谓词

if self.streamtype == "case1" {
    let predicatearray = defaults.object(forKey: "case1") as! [String]
    let predicate = NSPredicate(format: "UserID IN %@" , predicatearray)
} else if self.streamtype == "case2" {
    let predicate = NSPredicate(format: "TRUEPREDICATE", argumentArray: nil)
} else {
    let predicatearray = defaults.object(forKey: "case3") as! [String]
    let predicate = NSPredicate(format: "UserID IN %@", predicatearray)
}

let publicData = CKContainer.default().publicCloudDatabase
let query = CKQuery(recordType: "Post", predicate: predicate)

我得到一个错误，说：

“无法发送到NSPredicate类的抽象对象：创建具体实例！”

---

另外，它告诉我从未使用过谓词变量的初始化。我尝试了几种不同的方法编写函数，但这对我来说最有意义，因为我只需要在加载新信息时更新谓词，所以我将两个函数放在一个函数中。

您在

if{}

或

else{}

范围内定义谓词，这就是为什么它在范围外不可见的原因

var predicate : NSPredicate!
if self.streamtype == "case1" {
    let predicatearray = defaults.object(forKey: "case1") as! [String]
    predicate = NSPredicate(format: "UserID IN %@", predicatearray)
} else if self.streamtype == "case2" {
    predicate = NSPredicate(format: "TRUEPREDICATE", argumentArray: nil)
} else {
    let predicatearray = defaults.object(forKey: "case3") as! [String]
    predicate = NSPredicate(format: "UserID IN %@", predicatearray)
}

let publicData = CKContainer.default().publicCloudDatabase
let query = CKQuery(recordType: "Post", predicate: predicate)

---

您正在

if{}

或

else{}

范围内定义谓词，这就是它在范围外不可见的原因

var predicate : NSPredicate!
if self.streamtype == "case1" {
    let predicatearray = defaults.object(forKey: "case1") as! [String]
    predicate = NSPredicate(format: "UserID IN %@", predicatearray)
} else if self.streamtype == "case2" {
    predicate = NSPredicate(format: "TRUEPREDICATE", argumentArray: nil)
} else {
    let predicatearray = defaults.object(forKey: "case3") as! [String]
    predicate = NSPredicate(format: "UserID IN %@", predicatearray)
}

let publicData = CKContainer.default().publicCloudDatabase
let query = CKQuery(recordType: "Post", predicate: predicate)