objective-c - ios , 关于多 参数 枚举 的实现？

Question

我想实现 可以 传入 多参数枚举值的方法，例如

，请教一下，方法里面的逻辑判断

Answer 1

The UIRectCornerTopLeft and UIRectCornerTopRight shown in your code are actually not enumerations, but 按位掩码（bitmask）, and their definition is as follows:

typedef NS_OPTIONS(NSUInteger, UIRectCorner) {
    UIRectCornerTopLeft     = 1 << 0,
    UIRectCornerTopRight    = 1 << 1,
    UIRectCornerBottomLeft  = 1 << 2,
    UIRectCornerBottomRight = 1 << 3,
    UIRectCornerAllCorners  = ~0UL
};

The syntax of a bitwise mask (NS_OPTIONS) is the same as an enumeration (NS_ENUM), but the compiler will combine its values ​​| through a bitmask.

Editor:

For example, for the NS_OPTIONS of UIRectCorner above, according to your code, what you pass in is UIRectCornerTopLeft | UIRectCornerTopRight , then the processing code is roughly as follows:

UIRectCorner myRectCornerOptions = UIRectCornerTopLeft | UIRectCornerTopRight; // 你在方法里接收到值应该是这个。

// 对传入的 NS_OPTIONS 的处理逻辑：
if (myRectCornerOptions & UIRectCornerTopLeft) {
    // 包含了 UIRectCornerTopLeft。
} else {
    // 未包含 UIRectCornerTopLeft。
}
    
if (myRectCornerOptions & UIRectCornerTopRight) {
    // 包含了 UIRectCornerTopRight。
} else {
    // 未包含 UIRectCornerTopRight。
}