引用语法和值语法

DF945236-A37A-41AF-9CAA-B70C42969AB9.png

• Class为引用语法，而Struct为值语法

import UIKit

class Refrence{
    var s:String = "hello"
}

struct Value{
    var s:String = "hello"
}

let a = Refrence()

let b = a
b.s = "world"
print("Class \(a.s)")

let c = Value()

var d = c
d.s = "world"
print("Class \(c.s)")```


![Paste_Image.png](https://img.haomeiwen.com/i189984/2d21a6511b444c2e.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

###跨语言调用
- 首先当我们在Swift项目中创建OC、C、C++文件的时候，系统自动提示我们创建一个Bridge文件，用来引入其他类型文件的头文件

![Paste_Image.png](https://img.haomeiwen.com/i189984/87f3990211c614cc.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

- OC 与 Swift

- 先写一个简单的OC文件

import <Foundation/Foundation.h>

@interface ObjDemo : NSObject

• (NSString *)getTitle;
• (void)setTitle:(NSString *)title;

@end```

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 18.0px Menlo; color: #c81b13}p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 18.0px Menlo; color: #000000; min-height: 21.0px}p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 18.0px Menlo; color: #c42275}p.p4 {margin: 0.0px 0.0px 0.0px 0.0px; font: 18.0px Menlo; color: #000000}span.s1 {font-variant-ligatures: no-common-ligatures; color: #822d0f}span.s2 {font-variant-ligatures: no-common-ligatures}span.s3 {font-variant-ligatures: no-common-ligatures; color: #000000}span.s4 {font-variant-ligatures: no-common-ligatures; color: #c42275}

#import "ObjDemo.h"
#import "ViewController.swift"

@implementation ObjDemo{
    NSString *_title;
}

- (NSString *)getTitle{
    return _title;
}

- (void)setTitle:(NSString *)title{
    _title = title;
}

@end```

- 在Bridge文件中加入OC头文件

![Paste_Image.png](https://img.haomeiwen.com/i189984/0666afb64012bff1.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

- 在Swift文件中引用OC文件

```swift
let c = ObjDemo()
        c.setTitle("title")
        let t = c.getTitle() as String
        print(t)```

###Swift And C

- 先初始化一个C文件

```c
#include <stdio.h>

int getAnswer(){
    return 42;
}

// 在外界传递一个指针进来，然后在C函数中对这个指针进行修改
void generateAnswer(int * answer){
    *answer = 42;
}```

- 引入C文件的方法名到Bridge文件中

 ```C
int getAnswer();
void generateAnswer(int * answer);```

- Swift文件中调用

// Swift中对C的调用
let a = getAnswer()
print(a)

    // Swift中数据通过指针传递给C
    var pi:Int32 = 43
    generateAnswer(&pi)
    print(pi)```

Swift And C++

• 这里建议先使用OC文件将C++内容进行封装，然后再加入Bridge文件中进行使用

• 先初始化C++文件

• .cpp文件中

#include "Document.hpp"

void Document::setTitle(const std::string &title){
    title_ = title;
}

std::string Document::getTitle(){
    return title_;
}```

- .hpp文件中

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 18.0px Menlo; color: #822d0f}p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 18.0px Menlo; color: #000000; min-height: 21.0px}p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 18.0px Menlo; color: #000000}p.p4 {margin: 0.0px 0.0px 0.0px 0.0px; font: 18.0px Menlo; color: #c42275}p.p5 {margin: 0.0px 0.0px 0.0px 0.0px; font: 18.0px Menlo; color: #1e9421}span.s1 {font-variant-ligatures: no-common-ligatures}span.s2 {font-variant-ligatures: no-common-ligatures; color: #c81b13}span.s3 {font-variant-ligatures: no-common-ligatures; color: #c42275}span.s4 {font-variant-ligatures: no-common-ligatures; color: #000000}span.s5 {font-variant-ligatures: no-common-ligatures; color: #703daa}span.s6 {font-variant-ligatures: no-common-ligatures; color: #822d0f}

ifndef Document_hpp

define Document_hpp

include <string>

class Document {
public:
void setTitle(const std::string & title);
std::string getTitle();
private:
std::string title_;
};

endif /* Document_hpp */```

• 创建OC文件对其进行封装，这里要注意把.m文件改成.mm就可以正常使用C++的语法了

.mm

#import "DocumentWapper.h"
#include "Document.hpp"

@interface DocumentWapper(){
    Document doc;
}

@end

@implementation DocumentWapper

- (NSString *)getTitle{
    return [NSString stringWithUTF8String:doc.getTitle().c_str()];
}

- (void)setTitle:(NSString *)title{
    auto t = std::string([title cStringUsingEncoding:NSUTF8StringEncoding]);
    doc.setTitle(t);
}

@end```

.h暴露头文件

import <Foundation/Foundation.h>

@interface DocumentWapper : NSObject

• (NSString *)getTitle;

• (void)setTitle:(NSString *)title;

@end```

• 在Swift文件中调用

// Swift和C++交互 最好先用OC对C和C++进行封装
        let wa = DocumentWapper()
        wa.setTitle("C++_Title")
        let waT = wa.getTitle() as String
        print(waT)```

###ARC回收机制

![4B7273A1-C5C8-4C76-91BD-A88DD437E99B.png](https://img.haomeiwen.com/i189984/f689c344ba871a11.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

![AB50155C-2F6B-4E7A-BF47-196C6044F4F8.png](https://img.haomeiwen.com/i189984/9b6af764eb68c53f.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)