我正在寻找一种方法来比较指向c函数的指针.例如.：
let firstHandler = NSGetUncaughtExceptionHandler()
NSSetUncaughtExceptionHandler(onUncaughtException)
let secondHandler = NSGetUncaughtExceptionHandler()
if firstHandler == secondHandler {
debugPrint("equal")
}
更新==,也不是===有效
在目标C中,我可以表达如下：
NSUncaughtExceptionHandler *firstHandler = NSGetUncaughtExceptionHandler();
NSSetUncaughtExceptionHandler(onUncaughtException);
NSUncaughtExceptionHandler *secondHandler = NSGetUncaughtExceptionHandler();
if (firstHandler == secondHandler) {
NSLog(@"equal");
}
提前致谢
通常,您无法在Swift中比较函数的相等性.
但是,NSSetUncaughtExceptionHandler返回一个
但是,NSSetUncaughtExceptionHandler返回一个
(@convention(c) (NSException) -> Swift.Void)?
即(可选的)C兼容功能,并且这样的功能可以是
强制转换为(可选)原始指针
unsafeBitCast：
let ptr1 = unsafeBitCast(firstHandler,to: Optional<UnsafeRawPointer>.self) let ptr2 = unsafeBitCast(secondHandler,to: Optional<UnsafeRawPointer>.self)
然后可以比较平等
if ptr1 == ptr2 {.. }
一个独立的例子：
func exceptionHandler1(exception : NSException) { }
func exceptionHandler2(exception : NSException) { }
NSSetUncaughtExceptionHandler(exceptionHandler1)
let firstHandler = NSGetUncaughtExceptionHandler()
NSSetUncaughtExceptionHandler(exceptionHandler2)
let secondHandler = NSGetUncaughtExceptionHandler()
let ptr1 = unsafeBitCast(firstHandler,to: Optional<UnsafeRawPointer>.self)
print(ptr1 == ptr2) // false