Question

我正在尝试访问iOS私有函数_setApplicationIsOpaque:（仅供个人使用和测试）。

我已经实现了这段代码：

@_silgen_name("_setApplicationIsOpaque:") func _setApplicationIsOpaque(_ arg1: Bool)

let invokeSetApplicationIsOpaque: (Bool) -> Void = {
    // The Objective-C selector for the method.
    let selector: Selector = Selector(("_setApplicationIsOpaque:"))
    guard case let method = class_getInstanceMethod(UIApplication.self, selector), method != nil else {
        fatalError("Failed to look up \(selector)")
    }

    // Recreation of the method's implementation function.
    typealias Prototype = @convention(c) (AnyClass, Selector, Bool) -> Void
    let opaqueIMP = method_getImplementation(method)
    let function = unsafeBitCast(opaqueIMP, to: Prototype.self)

    // Capture the implemenation data in a closure that can be invoked at any time.
    return{ arg1 in function(UIApplication.self, selector, arg1)}
}()

extension UIApplication {
    func setApplicationIsOpaque(_ isOpaque: Bool) {
        return invokeSetApplicationIsOpaque(isOpaque)
    }
}

我在以下StackOverflow问题here中找到了访问私有iOS API的方法在GitHub的Access Private UIKit Function Without Using Bridging Header中。

问题是运行应用程序时出现错误

[UIApplication _setBackgroundStyle：]：无法识别的选择器发送到类0x10437f348

我找到了UIApplication this file的iOS私有API的标题。

Answer 1

- (void)_setApplicationIsOpaque:(BOOL)arg1;

是实例方法（UIApplication），如下所示最初的连字符-。实例方法被发送到实例班级本身，而不是班级本身。

Objective-C方法是带有两个隐藏参数的C函数，比较 Messaging 在“Objective-C运行时编程指南”中：

它还传递了两个隐藏的参数：


接收对象

方法的选择器

对于实例方法，“接收对象”是实例在您的情况下发送消息的UIApplication实例。（对于类方法，它将是类对象）。

因此Swift扩展方法setApplicationIsOpaque 必须将self传递给闭包，并且必须将其传递给实现方法的第一个参数：

let invokeSetApplicationIsOpaque: (UIApplication, Bool) -> Void = {
    // The Objective-C selector for the method.
    let selector = Selector(("_setApplicationIsOpaque:"))
    guard case let method = class_getInstanceMethod(UIApplication.self, selector), method != nil else {
        fatalError("Failed to look up \(selector)")
    }

    // Recreation of the method's implementation function.
    typealias Prototype = @convention(c) (UIApplication, Selector, Bool) -> Void
    let opaqueIMP = method_getImplementation(method)
    let function = unsafeBitCast(opaqueIMP, to: Prototype.self)

    // Capture the implemenation data in a closure that can be invoked at any time.
    return { (appl, arg1) in function(appl, selector, arg1)}
}()

extension UIApplication {
    func setApplicationIsOpaque(_ isOpaque: Bool) {
        return invokeSetApplicationIsOpaque(self, isOpaque)
    }
}

请注意，此处不需要_silgen_name声明。

@_silgen_name("_setApplicationIsOpaque:") func _setApplicationIsOpaque(_ arg1: Bool)

将Swift函数绑定到全局符号“_setApplicationIsOpaque”，哪个不存在。如果要添加对该函数的调用

_setApplicationIsOpaque(true)

然后构建应用程序将因链接器错误而失败：

Undefined symbols for architecture x86_64:  "__setApplicationIsOpaque:"

无法识别的选择器调用“_setApplicationIsOpaque：”

1 个答案: