当我遇到一个表达式
.KeyPathExpressionType
我不知道
.
在里面
.KeyPathExpressionType
指的是
.
当我在Google和stackoverflow中搜索“KeyPathExpressionType”时，什么也找不到。这和
.ConstantValueExpressionType
我什么也没找到。
每一个平等的比较
comparison.leftExpression.expressionType == .KeyPathExpressionType
和
comparison.rightExpression.expressionType == .ConstantValueExpressionType
在下面的代码中，生成一条错误消息，指出：
二进制运算符“=”不能应用于“NSExpression.ExpressionType”和“uu”类型的操作数
extension NSPredicate {
/**
Parses the predicate and attempts to generate a characteristic-value `HomeKitConditionType`.
- returns: An optional characteristic-value tuple.
*/
private func characteristic() -> HomeKitConditionType? {
guard let predicate = self as? NSCompoundPredicate else { return nil }
guard let subpredicates = predicate.subpredicates as? [NSPredicate] else { return nil }
guard subpredicates.count == 2 else { return nil }
var characteristicPredicate: NSComparisonPredicate? = nil
var valuePredicate: NSComparisonPredicate? = nil
for subpredicate in subpredicates {
if let comparison = subpredicate as? NSComparisonPredicate, comparison.leftExpression.expressionType == .KeyPathExpressionType && comparison.rightExpression.expressionType == .ConstantValueExpressionType {
switch comparison.leftExpression.keyPath {
case HMCharacteristicKeyPath:
characteristicPredicate = comparison
case HMCharacteristicValueKeyPath:
valuePredicate = comparison
default:
break
}
}
}
if let characteristic = characteristicPredicate?.rightExpression.constantValue as? HMCharacteristic,
characteristicValue = valuePredicate?.rightExpression.constantValue as? NSCopying {
return .Characteristic(characteristic, characteristicValue)
}
return nil
}
当我替换时，错误就消失了
comparison.leftExpression.expressionType == .KeyPathExpressionType
具有
comparison.leftExpression.expressionType.rawValue == NSExpression.ExpressionType.keyPath.rawValue
和
comparison.rightExpression.expressionType == .ConstantValueExpressionType
具有
comparison.rightExpression.expressionType.rawValue == NSExpression.ExpressionType.constantValue.rawValue
这是对的吗？有谁能告诉我这个问题的答案吗？
最佳答案
代码是过时的Swift 2代码。
用.KeyPathExpressionType替换.keyPath，用.ConstantValueExpressionType替换.constantValue
类型为NSExpression.ExpressionType，请阅读documentation