Question

因此，我正在学习swift以获得新工作并处理静态表视图，并决定尝试使用元组来跟踪已选择的单元格。但是我收到以下错误：

类型＆＃39;（section：Int，row：Int）＆＃39;的表达模式不能匹配类型＆＃39;（section：Int，row：Int）＆＃39;
的值

此错误是以下简化代码的结果

    let ABOUTPROTECTIONCELL = (section: 1, row: 0)
    let cellIdentifier = (section: indexPath.section, row: indexPath.row)

    switch cellIdentifier {
    case ABOUTPROTECTIONCELL:
        print("here")
    default:
        print("bleh")
    }

真正令人困惑的是，当我使用以下＆＃34;如果＆＃34;语句而不是switch语句一切正常，程序运行良好......

    if (cellIdentifier == CELL_ONE) {
        print("cell1")
    } else if (cellIdentifier == CELL_TWO) {
        print("cell2")
    } else if (cellIdentifier == CELL_THREE) {
        print("cell3")
    }

有没有办法用switch语句执行此操作，因为我发现它比if语句更优雅？非常好奇为什么这不起作用。提前谢谢！

Answer 1

解决方案1 

let ABOUTTROVPROTECTIONCELL = (section: 1, row: 0)
let cellIdentifier = (section: indexPath.section, row: indexPath.row)

switch cellIdentifier {
case (ABOUTTROVPROTECTIONCELL.section, ABOUTTROVPROTECTIONCELL.row):
    print("here")
default:
    print("bleh")
}

解决方案2

只需使用IndexPath结构及其初始值设定项即可创建ABOUTTROVPROTECTIONCELL

let ABOUTTROVPROTECTIONCELL = IndexPath(row: 0, section: 1)
let cellIdentifier = indexPath // Not necessary, you can just use indexPath instead

switch cellIdentifier {
case ABOUTTROVPROTECTIONCELL:
    print("here")
default:
    print("bleh")
}

解决方案3

为你的元组实现~= func：

typealias IndexPathTuple = (section: Int, row: Int)
func ~=(a: IndexPathTuple, b: IndexPathTuple) -> Bool {
    return a.section ~= b.section && a.row ~= b.row
}

let ABOUTTROVPROTECTIONCELL = (section: 1, row: 0)
let cellIdentifier = (section: indexPath.section, row: indexPath.row)

switch cellIdentifier {
case ABOUTTROVPROTECTIONCELL:
    print("here")
default:
    print("bleh")
}

Swift元组切换案例：类型模式不能匹配

1 个答案: