09-Runtime01

一、设置取值

• 1、 把三个变量的值存储在一个字节中

------------------------------------MJPerson.h-----------------------------------
#import <Foundation/Foundation.h>

@interface MJPerson : NSObject
//@property (assign, nonatomic, getter=isTall) BOOL tall;
//@property (assign, nonatomic, getter=isRich) BOOL rich;
//@property (assign, nonatomic, getter=isHansome) BOOL handsome;

- (void)setTall:(BOOL)tall;
- (void)setRich:(BOOL)rich;
- (void)setHandsome:(BOOL)handsome;

- (BOOL)isTall;
- (BOOL)isRich;
- (BOOL)isHandsome;

@end

------------------------------------MJPerson.m-----------------------------------
#import "MJPerson.h"

// &可以用来取出特定的位

// 0000 0111
//&0000 0100
//------
// 0000 0100

/** 掩码，一般用来按位与(&)运算的 **/
//#define MJTallMask 1 //0b00000001
//#define MJRichMask 2 //0b00000010
//#define MJHandsomeMask 4 //0b00000100

//#define MJTallMask 0b00000001
//#define MJRichMask 0b00000010
//#define MJHandsomeMask 0b00000100

//1往左移动0位（0b00000001）
#define MJTallMask (1<<0)
//1往左移动1位（0b00000010）
#define MJRichMask (1<<1)
//1往左移动2位（0b00000100）
#define MJHandsomeMask (1<<2)

@interface MJPerson()
{
    char _tallRichHansome;
}
@end

@implementation MJPerson


// 0010 1010
//&1111 1101
//----------
// 0010 1000

- (instancetype)init
{
    if (self = [super init]) {
        _tallRichHansome = 0b00000100;
    }
    return self;
}

- (void)setTall:(BOOL)tall
{
    if (tall) {
        _tallRichHansome |= MJTallMask;
        //相当于按位取或_tallRichHansome = _tallRichHansome | MJTallMask;
    } else {
        //~按位取反(例如：0b00001010 按位取反后为 0b11110101)
        _tallRichHansome &= ~MJTallMask;
    }
}

- (BOOL)isTall
{
    return !!(_tallRichHansome & MJTallMask);
    //(_tallRichHansome & MJTallMask)如果这位结果为1，那么!为假，再!为真，和原来保持一样。
}

- (void)setRich:(BOOL)rich
{
    if (rich) {
        _tallRichHansome |= MJRichMask;
    } else {
        _tallRichHansome &= ~MJRichMask;
    }
}

- (BOOL)isRich
{
    return !!(_tallRichHansome & MJRichMask);
}

- (void)setHandsome:(BOOL)handsome
{
    if (handsome) {
        _tallRichHansome |= MJHandsomeMask;
    } else {
        _tallRichHansome &= ~MJHandsomeMask;
    }
}

- (BOOL)isHandsome
{
    return !!(_tallRichHansome & MJHandsomeMask);
}

@end

-------------------------------------main.m---------------------------------------
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        MJPerson *person = [[MJPerson alloc] init];
//        person.rich = YES;
//        person.tall = NO;
//        person.handsome = NO;
        
        NSLog(@"tall:%d rich:%d hansome:%d", person.isTall, person.isRich, person.isHandsome);
        
//        NSLog(@"%zd", class_getInstanceSize([MJPerson class]));
    }
    return 0;
}

二、位域

• 2、设置取值采用第二种方案：位域（可读性较好）

------------------------------MJPerson.h-----------------------------
#import <Foundation/Foundation.h>

@interface MJPerson : NSObject
//@property (assign, nonatomic, getter=isTall) BOOL tall;
//@property (assign, nonatomic, getter=isRich) BOOL rich;
//@property (assign, nonatomic, getter=isHansome) BOOL handsome;

- (void)setTall:(BOOL)tall;
- (void)setRich:(BOOL)rich;
- (void)setHandsome:(BOOL)handsome;

- (BOOL)isTall;
- (BOOL)isRich;
- (BOOL)isHandsome;

@end
---------------------------------------MJPerson.m-----------------------------------
#import "MJPerson.h"

//#define MJTallMask (1<<0)
//#define MJRichMask (1<<1)
//#define MJHandsomeMask (1<<2)

@interface MJPerson()
{
    // 结构体支持位域
    struct {
        char tall : 1;//1：只占一位
        char rich : 1;
        char handsome : 1;
    } _tallRichHandsome;//结构体类型的成员变量_tallRichHandsome（这个结构体只有一个字节）
}
@end

@implementation MJPerson

- (void)setTall:(BOOL)tall
{
    _tallRichHandsome.tall = tall;
}

- (BOOL)isTall
{
    return !!_tallRichHandsome.tall;
}

- (void)setRich:(BOOL)rich
{
    _tallRichHandsome.rich = rich;
}

- (BOOL)isRich
{
    return !!_tallRichHandsome.rich;
}

- (void)setHandsome:(BOOL)handsome
{
    _tallRichHandsome.handsome = handsome;
}

- (BOOL)isHandsome
{
    return !!_tallRichHandsome.handsome;
}

@end

-------------------------------------main.m-----------------------------------
#import <Foundation/Foundation.h>
#import "MJPerson.h"
#import <objc/runtime.h>


int main(int argc, const char * argv[]) {
    @autoreleasepool {
        MJPerson *person = [[MJPerson alloc] init];
        person.rich = YES;
        person.tall = NO;
        person.handsome = NO;
        
        NSLog(@"tall:%d rich:%d hansome:%d", person.isTall, person.isRich, person.isHandsome);
    }
    return 0;
}

02的十六进制：00000010

三、共用体

共用体：共用一块内存。

---------------------------------------MJPerson.h---------------------------------------
#import <Foundation/Foundation.h>

@interface MJPerson : NSObject

- (void)setTall:(BOOL)tall;
- (void)setRich:(BOOL)rich;
- (void)setHandsome:(BOOL)handsome;
- (void)setThin:(BOOL)thin;

- (BOOL)isTall;
- (BOOL)isRich;
- (BOOL)isHandsome;
- (BOOL)isThin;

@end
---------------------------------------MJPerson.m------------------------------------------
#import "MJPerson.h"

#define MJTallMask (1<<0)
#define MJRichMask (1<<1)
#define MJHandsomeMask (1<<2)
#define MJThinMask (1<<3)

@interface MJPerson()
{
    union {
        int bits;
        
//        struct {//这个结构体用不到，可以不写，只不过是为了代码可读性
//            char tall : 4;
//            char rich : 4;
//            char handsome : 4;
//            char thin : 4;
//        };
    } _tallRichHandsome;
}
@end

@implementation MJPerson

- (void)setTall:(BOOL)tall
{
    if (tall) {
        _tallRichHandsome.bits |= MJTallMask;
    } else {
        _tallRichHandsome.bits &= ~MJTallMask;
    }
}

- (BOOL)isTall
{
    return !!(_tallRichHandsome.bits & MJTallMask);
}

- (void)setRich:(BOOL)rich
{
    if (rich) {
        _tallRichHandsome.bits |= MJRichMask;
    } else {
        _tallRichHandsome.bits &= ~MJRichMask;
    }
}

- (BOOL)isRich
{
    return !!(_tallRichHandsome.bits & MJRichMask);
}

- (void)setHandsome:(BOOL)handsome
{
    if (handsome) {
        _tallRichHandsome.bits |= MJHandsomeMask;
    } else {
        _tallRichHandsome.bits &= ~MJHandsomeMask;
    }
}

- (BOOL)isHandsome
{
    return !!(_tallRichHandsome.bits & MJHandsomeMask);
}



- (void)setThin:(BOOL)thin
{
    if (thin) {
        _tallRichHandsome.bits |= MJThinMask;
    } else {
        _tallRichHandsome.bits &= ~MJThinMask;
    }
}

- (BOOL)isThin
{
    return !!(_tallRichHandsome.bits & MJThinMask);
}

@end

---------------------------------------main.m----------------------------------
#import <Foundation/Foundation.h>
#import "MJPerson.h"
#import <objc/runtime.h>

union Date {
    int year;
    char month;
};


int main(int argc, const char * argv[]) {
    @autoreleasepool {
//        union Date date;
//        date.month = 1;
//        date.year = 2011;
//
        
        MJPerson *person = [[MJPerson alloc] init];
        person.thin = YES;
        person.rich = YES;
        person.handsome = NO;
        
        NSLog(@"thin:%d rich:%d hansome:%d", person.isThin, person.isRich, person.isHandsome);
    }
    return 0;
}

总结：

• 1、类对象、元类对象地址值最后三位一定是0
• 2、一个十六进制位代表四个二进制位