Question

我正在尝试将我的应用从8升级到Xcode 9.3.1并出现以下错误：

在“id＆lt; NSCopying＆gt;”类型的对象上找不到字典元素的预期方法

我的代码是：

// Normalize the blending mode to use for the key.
// *** Error on next three lines ***
id src = (options[CCBlendFuncSrcColor] ?: @(GL_ONE));
id dst = (options[CCBlendFuncDstColor] ?: @(GL_ZERO));
id equation = (options[CCBlendEquationColor] ?: @(GL_FUNC_ADD));

NSDictionary *normalized = @{
    CCBlendFuncSrcColor: src,
    CCBlendFuncDstColor: dst,
    CCBlendEquationColor: equation,

    // Assume they meant non-separate blending if they didn't fill in the keys.
    // *** Error on next line ***
    CCBlendFuncSrcAlpha: (options[CCBlendFuncSrcAlpha] ?: src),
    CCBlendFuncDstAlpha: (options[CCBlendFuncDstAlpha] ?: dst),
    CCBlendEquationAlpha: (options[CCBlendEquationAlpha] ?: equation),
};

有人能指出我正确的方向吗？我在代码中加粗了错误。

Answer 1

编译器认为options的类型为id<NSCopying>，而不是NSDictionary *，这是使用dictionary [key]语法所必需的。您的代码段不包括声明的位置，这是错误的位置。

Answer 2

您必须投射对象选项

    // Normalize the blending mode to use for the key.
id src = (((NSDictionary *)options)[CCBlendFuncSrcColor] ?: @(GL_ONE));
id dst = (((NSDictionary *)options)[CCBlendFuncDstColor] ?: @(GL_ZERO));
id equation = (((NSDictionary *)options)[CCBlendEquationColor] ?: @(GL_FUNC_ADD));

NSDictionary *normalized = @{
    CCBlendFuncSrcColor: src,
    CCBlendFuncDstColor: dst,
    CCBlendEquationColor: equation,

    // Assume they meant non-separate blending if they didn't fill in the keys.
    CCBlendFuncSrcAlpha: (((NSDictionary *)options)[CCBlendFuncSrcAlpha] ?: src),
    CCBlendFuncDstAlpha: (((NSDictionary *)options)[CCBlendFuncDstAlpha] ?: dst),
    CCBlendEquationAlpha: (((NSDictionary *)options)[CCBlendEquationAlpha] ?: equation),
};

在'id <nscopy>类型的对象上找不到字典元素的预期方法

2 个答案: