获得项目数为NS_ENUM的优雅的方式 [英] Elegant way of getting number of items for NS_ENUM
问题描述
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。
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_VALUE
NSArray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.
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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