在目标C中对枚举进行迭代? [英] Iteration over enum in Objective C?

问题描述

我有

enum Colour {
    white,
    pink,
    yellow,
    blue
} Colour;

我想做这样的事情:

for (int colour in Colour){
    // Do something here.
}

我可以这样做吗?如果可以，怎么办?感谢您的帮助！

Can I do this and if yes, how? Thanks for your help!

推荐答案

一个枚举来自C，而快速枚举是Objective-C 2.0的一个补充.它们无法协同工作.

an enum comes from C while fast enumeration was an addition of Objective-C 2.0.. they don't work together.

Type existingItem;
for ( existingItem in expression ) { statements }

表达式必须符合NSFastEnumeration协议，并且必须是对象！枚举的元素"不是对象.

expression must conform to the NSFastEnumeration Protocol and be an Object! "elements" of an enum are not objects.

有关更多信息，请参见此链接

see this link for more information Apple's Fast Enumeration Documents

检查此示例以了解快速枚举的工作原理:

check this example to see how fast enumeration works:

NSArray *array = [NSArray arrayWithObjects:
        @"One", @"Two", @"Three", @"Four", nil];

for (NSString *element in array) {
    NSLog(@"element: %@", element);
}

NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys:
    @"quattuor", @"four", @"quinque", @"five", @"sex", @"six", nil];

NSString *key;
for (key in dictionary) {
    NSLog(@"English: %@, Latin: %@", key, [dictionary objectForKey:key]);
}

这篇关于在目标C中对枚举进行迭代?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！