在目标 c 中切换 NSString 的大小写 [英] switch case on NSString in objective c

问题描述

我想在 NSString 中使用 case 语句请将我的代码更改为正确的代码

i want to use case statement with NSString please change my code to correct code

NSString *day = @"Wed";

switch (day) {
    case @"Sat":
        NSlog(@"Somthing...");
        break;

    case @"Sun":
        NSlog(@"Somthing else...");
        break;  
        .
        .
        .
        .

    default:
        break;
}

推荐答案

如果你想要一些比一长串条件更智能的调度，你可以使用块字典:

If you want some slightly smarter dispatch than a long list of conditionals you can use a dictionary of blocks:

NSString *key = @"foo";

void (^selectedCase)() = @{
    @"foo" : ^{
        NSLog(@"foo");
    },
    @"bar" : ^{
        NSLog(@"bar");
    },
    @"baz" : ^{
        NSLog(@"baz");
    },
}[key];

if (selectedCase != nil)
    selectedCase();

如果您有很长的案例列表并且经常这样做，那么这可能会带来很小的性能优势.你应该缓存字典，然后(不要忘记复制块).

If you have a really long list of cases and you do this often, there might be a tiny performance advantage in this. You should cache the dictionary, then (and don't forget to copy the blocks).

为了方便和简洁而牺牲易读性，这是一个将所有内容都放入单个语句并添加默认情况的版本:

Sacrificing legibility for convenience and brevity here's a version that fits everything into a single statement and adds a default case:

((void (^)())@{
    @"foo" : ^{
        NSLog(@"foo");
    },
    @"bar" : ^{
        NSLog(@"bar");
    },
    @"baz" : ^{
        NSLog(@"baz");
    },
}[key] ?: ^{
    NSLog(@"default");
})();

我更喜欢前者.

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