SwiftError

SwiftError 允许您创建符合 Error、CustomNSError 和 LocalizedError 协议的错误，而无需声明您自己的错误类型。

便利设施

提供两个工具函数作为示例，演示如何通过利用错误类型来简化源代码。

• cast<T, U>(_ subject: T) -> U

  在处理远程API时，再也不必强制转换。相反，let string = any as! String 变为

  let string = try cast(any) as String

• unwrap<T>(_ optional: T?) -> T

  在工作于遗留接口时，改写 let some = optional! 为

  let some = try unwrap(optional)

示例

1. 编译示例

   swiftc SwiftError/*.swift main.swift -o demo

2. 运行示例

   ./demo
   

样本输出

Demo print output
-----------------
Undefined error -10001, demoThrow(), main.swift:L5
["key": "val", "float": 3.1, "int": 256]

Demo debugPrint output
----------------------
Undefined error -10001, demoThrow(), main.swift:L5
0   main                                0x000000010f1be165 $S4main9demoThrowyyKF + 501
1   main                                0x000000010f1bc96d main + 45
{
    float = "3.1";
    int = 256;
    key = val;
}

Demo cast print output
----------------------
Unexpected String in place of Int -10000, demoCast(), main.swift:L22

Demo cast debugPrint output
---------------------------
Unexpected String in place of Int -10000, demoCast(), main.swift:L22
0   main                                0x000000010f1bf015 $S4main4cast_4file8function4lineq_x_S2SSitKr0_lF + 1189
1   main                                0x000000010f1be2f9 $S4main8demoCastyyKF + 217
2   main                                0x000000010f1bca55 main + 277

Demo unwrap print output
------------------------
Unexpected nil for optional Any -9999, demoUnwrap(), main.swift:L40

Demo unwrap debugPrint output
-----------------------------
Unexpected nil for optional Any -9999, demoUnwrap(), main.swift:L40
0   main                                0x000000010f1be9fb $S4main6unwrap_4file8function4linexxSg_S2SSitKlF + 891
1   main                                0x000000010f1be464 $S4main10demoUnwrapyyKF + 212
2   main                                0x000000010f1bcb3d main + 509