有没有得到一个NS_ENUM项目总数的优雅的方式?和最大值?
一些例子:
的typedef NS_ENUM(NSInteger的,MyEnum){ MyEnumA = 0, MyEnumB = 1, MyEnumC = 2};// NumberOfItems(MyEnum) - > 3,MaximumValue(MyEnum) - GT; 2。的typedef NS_ENUM(NSInteger的,MyEnum){ MyEnumA, MyEnumB, MyEnumC};// NumberOfItems(MyEnum) - > 3,MaximumValue(MyEnum) - GT; 2。的typedef NS_ENUM(NSInteger的,MyEnum){ MyEnumA = 4, MyEnumB, MyEnumC};// NumberOfItems(MyEnum) - > 3,MaximumValue(MyEnum) - GT; 6。的typedef NS_ENUM(NSInteger的,MyEnum){ MyEnumA = 0, MyEnumB = 2, MyEnumC = 4};// NumberOfItems(MyEnum) - > 3,MaximumValue(MyEnum) - GT; 4。解决方案
不幸的是,C枚举(其中 NS_ENUM 宏是一个发电机)都相当简单,没有反思
如果您的枚举值是连续的,它的简单让使用极限值的项目数:
的typedef NS_ENUM(NSInteger的,MyEnum){ MyEnumA = 0, MyEnumB, MyEnumC, MyEnumMax};NSUInteger numItems的= MyNumMax;然而,这并不是因为当你写一个开关的理想解决方案,你会得到一个警告,如果你不添加情况MyEnumMax:(或默认值:)。
您最好的选择就是为每个枚举创建信息功能:
的typedef NS_ENUM(NSInteger的,MyEnum){ MyEnumA = 0, MyEnumB = 2, MyEnumC = 4,};NSUInteger MyEnumSize(){ 返回3;}您也可以使用如的X宏一些高级宏观技术来生成这个函数动态。
大警告:X-宏并不简单,不容易阅读,但他们是强大的。举例如下:
MyEnum.h
的#define MY_ENUM_DEFINITIONS \\ NS_ENUM_X_VALUE(MyEnumA,= 0)\\ NS_ENUM_X_VALUE(MyEnumB,)\\ NS_ENUM_X_VALUE(MyEnumC,= 4)#定义NS_ENUM_X_VALUE(__ NAME__,__INT_VALUE__)__name__ __INT_VALUE__,的typedef NS_ENUM(NSInteger的,MyEnum){ MY_ENUM_DEFINITIONS};和#undef NS_ENUM_X_VALUE* NSString的NSStringFromMyEnum(MyEnum值);NSArray的* MyEnumValues();NSUInteger MyEnumSize();NSUInteger MyEnumMin();NSUInteger MyEnumMax();MyEnum.m
的#define NS_ENUM_X_VALUE(__ NAME__,__INT_VALUE__)__name__] = @#__ NAME__,静态的NSString * MyEnumStringTable [] = { MY_ENUM_DEFINITIONS};和#undef NS_ENUM_X_VALUE* NSString的NSStringFromMyEnum(MyEnum值){ 返回MyEnumStringTable [值];}#定义NS_ENUM_X_VALUE(__ NAME__,__INT_VALUE__)@(__ NAME__)静态NSOrderedSet * MyEnumValueSet(){ 静态NSOrderedSet * valueSet =零; 静态dispatch_once_t onceToken; dispatch_once(安培; onceToken,^ { valueSet = [[NSOrderedSet页头] initWithObjects: MY_ENUM_DEFINITIONS 零]; }); 返回valueSet;}和#undef NS_ENUM_X_VALUENSArray的* MyEnumValues(){ 返回[MyEnumValueSet()数组];}NSUInteger MyEnumSize(){ 返回MyEnumValueSet()计数。}NSUInteger MyEnumMin(){ 返回[MyEnumValueSet()firstObject unsignedIntegerValue。]}NSUInteger MyEnumMax(){ 返回[MyEnumValueSet()lastObject unsignedIntegerValue。]}用法
的NSLog(@MyEnum大小:%@,@(MyEnumSize()));的NSLog(@MyEnum分钟:%@,@(MyEnumMin()));的NSLog(@MyEnum最大值:%@,@(MyEnumMax()));的NSLog(@MyEnumC值字符串:%@,NSStringFromMyEnum(MyEnumC));对于(NSNumber的*在MyEnumValues值()){ 的NSLog(@价值上市:%@ = GT;%@,NSStringFromMyEnum([值unsignedIntegerValue]),价值);}现在可以修改/添加/删除值在标题中,你所有的功能将被自动更新。
Is there an elegant way of getting the total number of items in a NS_ENUM? And the maximum value?
Some examples:
typedef NS_ENUM(NSInteger, MyEnum) { MyEnumA = 0, MyEnumB = 1, MyEnumC = 2 }; // NumberOfItems(MyEnum) -> 3, MaximumValue(MyEnum) -> 2. typedef NS_ENUM(NSInteger, MyEnum) { MyEnumA, MyEnumB, MyEnumC }; // NumberOfItems(MyEnum) -> 3, MaximumValue(MyEnum) -> 2. typedef NS_ENUM(NSInteger, MyEnum) { MyEnumA = 4, MyEnumB, MyEnumC }; // NumberOfItems(MyEnum) -> 3, MaximumValue(MyEnum) -> 6. typedef NS_ENUM(NSInteger, MyEnum) { MyEnumA = 0, MyEnumB = 2, MyEnumC = 4 }; // NumberOfItems(MyEnum) -> 3, MaximumValue(MyEnum) -> 4.解决方案
Unfortunately, C enums (which NS_ENUM macro is a generator for) are rather simple, with no reflection.
If your enum values are consecutive, it's simple to get the number of items using limit values:
typedef NS_ENUM(NSInteger, MyEnum) { MyEnumA = 0, MyEnumB, MyEnumC, MyEnumMax }; NSUInteger numItems = MyNumMax;However, this is not an ideal solution because when you write a switch, you will get a warning if you don't add a case MyEnumMax: (or default:).
Your best option then is to create info functions for every enum:
typedef NS_ENUM(NSInteger, MyEnum) { MyEnumA = 0, MyEnumB = 2, MyEnumC = 4, }; NSUInteger MyEnumSize() { return 3; }You could also use some advanced macro techniques like X-macros to generate this function dynamically.
Big warning: X-macros are not simple, not easily readable but they are powerful. Example follows:
MyEnum.h
#define MY_ENUM_DEFINITIONS \ NS_ENUM_X_VALUE(MyEnumA, = 0) \ NS_ENUM_X_VALUE(MyEnumB,) \ NS_ENUM_X_VALUE(MyEnumC, = 4) #define NS_ENUM_X_VALUE(__NAME__, __INT_VALUE__) __NAME__ __INT_VALUE__, typedef NS_ENUM(NSInteger, MyEnum) { MY_ENUM_DEFINITIONS }; #undef NS_ENUM_X_VALUE NSString * NSStringFromMyEnum(MyEnum value); NSArray * MyEnumValues(); NSUInteger MyEnumSize(); NSUInteger MyEnumMin(); NSUInteger MyEnumMax();MyEnum.m
#define NS_ENUM_X_VALUE(__NAME__, __INT_VALUE__) [__NAME__] = @#__NAME__, static NSString* MyEnumStringTable[] = { MY_ENUM_DEFINITIONS }; #undef NS_ENUM_X_VALUE NSString * NSStringFromMyEnum(MyEnum value) { return MyEnumStringTable[value]; } #define NS_ENUM_X_VALUE(__NAME__, __INT_VALUE__) @(__NAME__), static NSOrderedSet * MyEnumValueSet() { static NSOrderedSet *valueSet = nil; static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ valueSet = [[NSOrderedSet alloc] initWithObjects: MY_ENUM_DEFINITIONS nil]; }); return valueSet; } #undef NS_ENUM_X_VALUE NSArray *MyEnumValues() { return [MyEnumValueSet() array]; } NSUInteger MyEnumSize() { return MyEnumValueSet().count; } NSUInteger MyEnumMin() { return [MyEnumValueSet().firstObject unsignedIntegerValue]; } NSUInteger MyEnumMax() { return [MyEnumValueSet().lastObject unsignedIntegerValue]; }Usage
NSLog(@"MyEnum size: %@", @(MyEnumSize())); NSLog(@"MyEnum min: %@", @(MyEnumMin())); NSLog(@"MyEnum max: %@", @(MyEnumMax())); NSLog(@"MyEnumC value to string: %@", NSStringFromMyEnum(MyEnumC)); for (NSNumber *value in MyEnumValues()) { NSLog(@"Value listing: %@ => %@", NSStringFromMyEnum([value unsignedIntegerValue]), value); }Now you can modify/add/remove values in the header and all your functions will be updated automatically.
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