iOS 的 c++，c，obj-C，swift 混用 （转载）

转载自： https://stackoverflow.com/questions/32541268/can-i-have-swift-objective-c-c-and-c-files-in-the-same-xcode-project/32546879#32546879

Can I have Swift, Objective-C, C and C++ files in the same Xcode project?

Can all 4 languages be used in the same project at all, and if so how?

There are similar questions in the flavor: Can I mix Swift with C++? Like the Objective - C .mm filesto which the accepted answer is no.

Using Bridging Header adequately, .h that do not contain C++ statements, Objective-Cwrappers when .h do contain C++, .mm files to do the actual wrapping of C++ classes, and .swift, can the 4 languages (5 if you include Objective-C++) build and link into a single executable?

YES.

You can mix Swift, C, C++, Objective-C & Objective-C++ files in the same Xcode project.

C

// Declaration: C.h#ifndef C_h#define C_h#ifdef __cplusplusextern "C" {#endif    void hello_c(const char * name);#ifdef __cplusplus}#endif#endif /* C_h */// Definition: C.c#include "C.h"#include <stdio.h>void hello_c(const char * name) {    printf("Hello %s in C\n", name);}

C++

// Declaration: CPP.hpp#pragma once#include <string>class CPP {public:    void hello_cpp(const std::string& name);};// Definition: CPP.cpp#include "CPP.hpp"#include <iostream>using namespace std;void CPP::hello_cpp(const std::string& name) {    cout << "Hello " << name << " in C++" << endl;}

Objective-C wrapper for C++

// Declaration: CPP-Wrapper.h#import <Foundation/Foundation.h>@interface CPP_Wrapper : NSObject- (void)hello_cpp_wrapped:(NSString *)name;@end// Definition: CPP-Wrapper.mm#import "CPP-Wrapper.h"#include "CPP.hpp"@implementation CPP_Wrapper- (void)hello_cpp_wrapped:(NSString *)name {    CPP cpp;    cpp.hello_cpp([name cStringUsingEncoding:NSUTF8StringEncoding]);}@end

Objective-C

// Declaration: Objective-C.h#import <Foundation/Foundation.h>@interface Objective_C : NSObject- (void)hello_objectiveC:(NSString *)name;@end// Definition: Objective-C.m#import "Objective-C.h"@implementation Objective_C- (void)hello_objectiveC:(NSString*)name {    printf("Hello %s in Objective-C\n", [name cStringUsingEncoding:NSUTF8StringEncoding]);}@end

Objective-C++

// Declaration: Objective-CPP.h#import <Foundation/Foundation.h>@interface Objective_CPP : NSObject- (void)hello_objectiveCpp:(NSString *)name;@end// Definition: Objective-CPP.mm#include <iostream>#import "Objective-CPP.h"using namespace std;@implementation Objective_CPP- (void)hello_objectiveCpp:(NSString *)name {    cout << "Hello " << [name cStringUsingEncoding:NSUTF8StringEncoding] << " in Objective-C++\n";}@end

Swift

// Declaration & definition: Swift.swiftfunc hello_swift(_ name: String) {    print("Hello \(name) in Swift")}

Bridging-Header.h

Cannot import CPP.hpp header file, not because of it's naming convention, but because it contains the class keyword.

#import "C.h"#import "CPP-Wrapper.h"#import "Objective-C.h"#import "Objective-CPP.h"

Invocation from Swift

// Invoke Chello_c("World".cStringUsingEncoding(NSUTF8StringEncoding))// Can't Invoke C++ without a wrapper// CPP().hello_cpp("World".cStringUsingEncoding(NSUTF8StringEncoding))// Invoke C++ through Objective-CCPP_Wrapper().hello_cpp_wrapped("World")// Invoke Objective-CObjective_C().hello_objectiveC("World")// Invoke Objective-C++Objective_CPP().hello_objectiveCpp("World")// Invoke SwiftSwift().hello_swift("World")

.h (Headers)

(See item 3 in this Stack Overflow answer)

.h: this is the tricky part, since they are ambiguously used for all flavors of C, ++ or not, Objective or not. When a .h does not contain a single C++ keyword, like class, it can be added to the ...Bridging-Header.h, and will expose whatever function the corresponding .c or .cpp functionalities it declares. Otherwise, that header must be wrapped in either a pure C or Objective-C API.

Output

Hello World in CHello World in C++Hello World in Objective-CHello World in Objective-C++Hello World in Swift

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Comments

Cy-4AH:

Yes. You only need wrap C++ into C or Objective-C to use in Swift.

Tommy

Indeed, I have a project that does exactly that. C++ for the thrust of the abstract cross-platform model stuff with some C parts underneath; Objective-C to wrap the C++ classes for Swiftpurposes, Swift to bind all that to a subclass of NSDocument, with some custom views that interrogate the C stuff.

MaddTheSane

Added the extern "C" wrapper as per your excellent suggestion. To invoke the C method void hello_c(const char * name) from C++ method hello_cpp(const std::string& name), add #include "C.h" and call hello_c(name.c_str());.

Keith Adler

The new SO-32541268: Now with parameters!