OC底层 - runtime 一个char变量按位保存多个BOOL变量值

在arm64之后, 优化了isa指针实现, 使用共同体实现isa, 可以节省内存:

以下使用一个char变量保存多个BOOL变量的值, 实现代码:

///左移操作
#define LPTail (1<<0)
#define LPRich (1<<1)
#define LPHandsome (1<<2)

//
//  Person.m
//  demo007_runtime_isa_共用体
//
//  Created by Batac on 2020/12/7.
//




#import "Person.h"


@interface Person()
{
    //一个字节   可以表示8个BOOL变量
    char _tailRichHandsome;
}
@end

@implementation Person

-(BOOL)getTail{
    return !!(_tailRichHandsome & LPTail);
}

-(void)setTail:(BOOL)tail{
    if (tail) {
        _tailRichHandsome = _tailRichHandsome | LPTail;
    }else{
        _tailRichHandsome = _tailRichHandsome & ~LPTail;
    }
}

-(BOOL)getRich{
    return !!(_tailRichHandsome & LPRich);
}

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

-(BOOL)getHandsome{
    return !!(_tailRichHandsome & LPHandsome);
}

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

@end