iOS开发 枚举类型NS_ENUM和NS_OPTIONS的区别

NS_ENUM

通用枚举值

typedef NS_ENUM(NSInteger, UIControlContentHorizontalAlignment) {    UIControlContentHorizontalAlignmentCenter = 0,    UIControlContentHorizontalAlignmentLeft   = 1,    UIControlContentHorizontalAlignmentRight  = 2,    UIControlContentHorizontalAlignmentFill   = 3,};

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NS_OPTIONS

位移相关操作的枚举值

typedef NS_OPTIONS(NSUInteger, UIControlState) {    UIControlStateNormal       = 0,    UIControlStateHighlighted  = 1 << 0,    UIControlStateDisabled     = 1 << 1,    UIControlStateSelected     = 1 << 2,    UIControlStateApplication  = 0x00FF0000,    UIControlStateReserved     = 0xFF000000};

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• 通常情况下我们用的枚举是NS_ENUM
• 当一个枚举变量可能要代表多个属性的时候，就要用到NS_OPTIONS(NS_OPTIONS代表的也是一个值，只不过是两个或多个值按位移后的值)

self.tableView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;

共

同

进

步

O(∩_∩)O

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