iOS 开发使用OC的奇淫技巧

实现快速变更类名，而不需要更改文件名

#define ABC(x) ModuleName##x // ##
符号是将参数x作为字符串与 ##符号前面的字符串拼接在一起转成一个字符串

#define MyPrint(x) std::cout << #x << " is " << x <<std::endl; // #符号会将跟在后面的参数转成字符串，相当与在参数x上加上""，形成"x"

class ABC(class1) {

public:

    ABC(class1)(std::string name) {

        this->s_name = name;

    }

    void printInfo();

private:

    std::string s_name;

};

void ABC(class1)::printInfo() {

    std::cout << "My name is " << s_name << std::endl;

}

ABC(class1) test1 =  ABC(class1)("haha");

    test1.printInfo();

    int i_num = 1021;

    MyPrint(i_num)

- (instancetype)initWithName:(NSString *)name age:(NSUInteger)age NS_DESIGNATED_INITIALIZER;

NS_DESIGNATED_INITIALIZER，将方法指定为初始化的方法

- (instancetype)init NS_UNAVAILABLE;

NS_UNAVAILABLE将方法注释为不可用，编译器会在编译时报错,且Xcode智能提示不会给出提示

- (void)method1:(NSString *)p1 __deprecated;

__deprecated
将方法提示已经为不推荐使用

#if __has_feature(objc_arc)

- (void)methodWithARC;

#else

- (void)methodNoARC;

#endif

__has_feature(arg)
根据整个工程中是不是才有某种编译特性决定返回true or false，通常参数使用objc_arc

#pragma clang diagnostic push

#pragma clang diagnostic ignored "-Wdeprecated-declarations"

 // code  //
用来消除因为方法被标记为__deprecated,而带来的编译警告

#pragma clang diagnostic pop

循环引用

"-Warc-retain-cycles"

未使用变量

"-Wunused-variable"

指针类型不兼容

"-Wincompatible-pointer-types"

根据对应平台的操作系统版本进行条件编译

#if __IPHONE_OS_VERSION_MAX_ALLOWED(AvailabilityInternal.h) >= __IPHONE_10_0(Availability.h,系统版本存在的头文件) 

#import <UserNotifications/UserNotifications.h>

#endif

备注：关于更多iOS 使用OC编码使用的宏，可以查阅：

异常宏：

/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/System/Library/Frameworks/Foundation.framework/Versions/C/Headers/NSException.h

运行时宏:(一般是用来改变编译条件)

/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/System/Library/Frameworks/Foundation.framework/Versions/C/Headers/NSObjCRuntime.h

/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/TargetConditionals.h

/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/Availability.h

/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/AvailabilityInternal.h