考虑私有C函数 _UICreateScreenUIImage
,返回一个 UIImage
当前设备屏幕的快照:
OBJC_EXTERN UIImage *_UICreateScreenUIImage(void) NS_RETURNS_RETAINED;
我可以将它放在一个桥接头中,并在Swift中访问它,如下所示:
MyApp的桥接,Header.h
@import UIKit;
UIImage *_UICreateScreenUIImage(void) NS_RETURNS_RETAINED;
MyClass.swift
let image = _UICreateScreenUIImage()
print(image) // <UIImage: 0x7fc4ba6081c0>, {375, 667}
有没有办法可以访问 _UICreateScreenUIImage
在纯粹的Swift中没有使用桥接头?
最初的想法是创建一个扩展 UIImage
,但扩展期望我在扩展中声明函数体:
extension UIImage {
public func _UICreateScreenUIImage(_: Void) -> UIImage // "Expected '{' in body of function declaration"
}
这种实现无论如何都是有缺陷的 _UICreateScreenUIImage
不是一个方法 UIImage
。
是否可以在纯Swift中公开和访问此方法?
人们似乎把我的问题与“如何截取屏幕截图?”混淆了。那不是我要问的。我问我如何访问类似的方法 UIImage *_UICreateScreenUIImage(void);
在斯威夫特。它可以是任何私有方法,例如 +(UIImage *)_deviceSpecificImageNamed:(NSString *)name inBundle:(NSBundle *)bundle;
要么 +(UIImage *)_pu_PhotosUIImageNamed:(NSString *)name;
。
它比你想象的容易得多:
@asmname("_UICreateScreenUIImage")
func _UICreateScreenUIImage() -> UIImage
// That's it – go ahead and call it:
_UICreateScreenUIImage()
当它发生的时候, @asmname
实际上 只是 已在2.3版本中更改为 @_silgen_name
,所以准备相应调整:
@_silgen_name("_UICreateScreenUIImage")
func _UICreateScreenUIImage() -> UIImage
据我所知, @_silgen_name
不提供Objective-C方法的解决方案。为此,还有更强大的Objective-C运行时API:
let invokeImageNamed: (String, NSTimeInterval) -> UIImage? = {
// The Objective-C selector for the method.
let selector: Selector = "animatedImageNamed:duration:"
guard case let method = class_getClassMethod(UIImage.self, selector)
where method != nil else { fatalError("Failed to look up \(selector)") }
// Recreation of the method's implementation function.
typealias Prototype = @convention(c) (AnyClass, Selector, NSString, NSTimeInterval) -> UIImage?
let opaqueIMP = method_getImplementation(method)
let function = unsafeBitCast(opaqueIMP, Prototype.self)
// Capture the implemenation data in a closure that can be invoked at any time.
return { name, interval in function(UIImage.self, selector, name, interval) }
}()
extension UIImage {
// Convenience method for calling the closure from the class.
class func imageNamed(name: String, interval: NSTimeInterval) -> UIImage? {
return invokeImageNamed(name, interval)
}
}
UIImage.imageNamed("test", interval: 0)
处理 NS_RETURNS_RETAINED
,这不会为您生成。相反,您可以使用返回类型 Unmanaged
,并在功能中包装,以方便您:
@_silgen_name("_UICreateScreenUIImage")
func _UICreateScreenUIImage() -> Unmanaged<UIImage>
func UICreateScreenUIImage() -> UIImage {
return _UICreateScreenUIImage().takeRetainedValue()
}
它比你想象的容易得多:
@asmname("_UICreateScreenUIImage")
func _UICreateScreenUIImage() -> UIImage
// That's it – go ahead and call it:
_UICreateScreenUIImage()
当它发生的时候, @asmname
实际上 只是 已在2.3版本中更改为 @_silgen_name
,所以准备相应调整:
@_silgen_name("_UICreateScreenUIImage")
func _UICreateScreenUIImage() -> UIImage
据我所知, @_silgen_name
不提供Objective-C方法的解决方案。为此,还有更强大的Objective-C运行时API:
let invokeImageNamed: (String, NSTimeInterval) -> UIImage? = {
// The Objective-C selector for the method.
let selector: Selector = "animatedImageNamed:duration:"
guard case let method = class_getClassMethod(UIImage.self, selector)
where method != nil else { fatalError("Failed to look up \(selector)") }
// Recreation of the method's implementation function.
typealias Prototype = @convention(c) (AnyClass, Selector, NSString, NSTimeInterval) -> UIImage?
let opaqueIMP = method_getImplementation(method)
let function = unsafeBitCast(opaqueIMP, Prototype.self)
// Capture the implemenation data in a closure that can be invoked at any time.
return { name, interval in function(UIImage.self, selector, name, interval) }
}()
extension UIImage {
// Convenience method for calling the closure from the class.
class func imageNamed(name: String, interval: NSTimeInterval) -> UIImage? {
return invokeImageNamed(name, interval)
}
}
UIImage.imageNamed("test", interval: 0)
处理 NS_RETURNS_RETAINED
,这不会为您生成。相反,您可以使用返回类型 Unmanaged
,并在功能中包装,以方便您:
@_silgen_name("_UICreateScreenUIImage")
func _UICreateScreenUIImage() -> Unmanaged<UIImage>
func UICreateScreenUIImage() -> UIImage {
return _UICreateScreenUIImage().takeRetainedValue()
}