位移枚举

1     << : 左移,比如1<<n,表示1往左移n位，即数值大小2的n次方; 例如 : 0b0001 << 1 变为了 0b0010
2     >> : 右移,类似左移,数值大小除以2的n次方
3     &  : 按位与,1与任意数等于任意数本身,0与任意数等于0,即1&x=x,0&x=0
4     |  : 按位或,x|y中只要有一个1则结果为1；反之为0
5     ^  : 按位异或,x^y相等则为0,不等则为1

typedef NS_OPTIONS(NSUInteger, BDRequestOptions) {
    BDRequestOptionSuccess     = 1 << 0,
    BDRequestOptionFailure     = 1 << 1,
    BDRequestOptionProcessing  = 1 << 2,
    BDRequestOptionAnimate     = 1 << 3,
};

// 首先定义一组
typedef NS_OPTIONS(NSUInteger, BDRequestOptions) {
    BDRequestOptionSuccess     = 1 << 0,
    BDRequestOptionFailure     = 1 << 1,
    BDRequestOptionProcessing  = 1 << 2,
    BDRequestOptionAnimate     = 1 << 3,
};

// 然后调用我们定义的方法
#pragma mark - View lifeCycle
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor orangeColor];
    
    [self test:BDRequestOptionSuccess | BDRequestOptionFailure | BDRequestOptionProcessing | BDRequestOptionAnimate];
}

- (void)test:(BDRequestOptions)type {
    if (type & BDRequestOptionSuccess) {
        NSLog(@"BDRequestOptionSuccess");
    }
    if (type & BDRequestOptionFailure) {
        NSLog(@"BDRequestOptionFailure");
    }
    if (type & BDRequestOptionProcessing) {
        NSLog(@"BDRequestOptionProcessing");
    }
    if (type & BDRequestOptionAnimate) {
        NSLog(@"BDRequestOptionAnimate");
    }
}

// 查看打印结果:
2016-04-04 14:09:44.946 OC测试[5869:719056] BDRequestOptionSuccess
2016-04-04 14:09:44.947 OC测试[5869:719056] BDRequestOptionFailure
2016-04-04 14:09:44.947 OC测试[5869:719056] BDRequestOptionProcessing
2016-04-04 14:09:44.947 OC测试[5869:719056] BDRequestOptionAnimate

// 首先定义一组
typedef NS_OPTIONS(NSUInteger, BDRequestOptions) {
    BDRequestOptionSuccess     = 0b0001 << 0,
    BDRequestOptionFailure     = 0b0010 << 1,
    BDRequestOptionProcessing  = 0b0100 << 2,
    BDRequestOptionAnimate     = 0b1000 << 3,
};

#pragma mark - View lifeCycle
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor orangeColor];
    
    [self test:BDRequestOptionSuccess | BDRequestOptionFailure | BDRequestOptionProcessing | BDRequestOptionAnimate];
    /** 
     BDRequestOptionSuccess | BDRequestOptionFailure | BDRequestOptionProcessing | BDRequestOptionAnimate
     
     等同于:0b0001 |
           0b0010 |
           0b0100 |
           0b1000 
     结果为:0b1111
     */
}

- (void)test:(BDRequestOptions)type {
    // 0b1111 & 0b0001 --->  0b0b0001
    if (type & BDRequestOptionSuccess) {
        NSLog(@"BDRequestOptionSuccess");
    }
    // 0b1111 & 0b0010 --->  0b0b0010
    if (type & BDRequestOptionFailure) {
        NSLog(@"BDRequestOptionFailure");
    }
    // 0b1111 & 0b0100 --->  0b0b0100
    if (type & BDRequestOptionProcessing) {
        NSLog(@"BDRequestOptionProcessing");
    }
    // 0b1111 & 0b1000 --->  0b0b1000
    if (type & BDRequestOptionAnimate) {
        NSLog(@"BDRequestOptionAnimate");
    }
}

// 传0，不打印任何值
[self test:0];

NSString *string = @"Learning";
    [string boundingRectWithSize:CGSizeMake(CGRectGetWidth(self.view.frame), MAXFLOAT)
                         options:NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingTruncatesLastVisibleLine
                      attributes:@{NSFontAttributeName : [UIFont systemFontOfSize:12.f]}
                         context:nil];

 1     // 对传入的option逻辑处理
 2     if (option & NSStringDrawingUsesLineFragmentOrigin) {
 3         // 包含   NSStringDrawingUsesLineFragmentOrigin
 4     } else {
 5         // 未包含 NSStringDrawingUsesLineFragmentOrigin
 6     }
 7     if (option & NSStringDrawingTruncatesLastVisibleLine) {
 8         // 包含   NSStringDrawingTruncatesLastVisibleLine
 9     } else {
10         // 未包含 NSStringDrawingTruncatesLastVisibleLine
11     }