如何获取NSString的子字符串？ [英] How to get substring of NSString?

问题描述

如果我想从NSString @值获取值：hello World：value，我应该使用什么？

If I want to get a value from the NSString @"value:hello World:value", what should I use?

我想要的返回值是 @hello World。

推荐答案

选项1：

NSString *haystack = @"value:hello World:value";
NSString *haystackPrefix = @"value:";
NSString *haystackSuffix = @":value";
NSRange needleRange = NSMakeRange(haystackPrefix.length,
                                  haystack.length - haystackPrefix.length - haystackSuffix.length);
NSString *needle = [haystack substringWithRange:needleRange];
NSLog(@"needle: %@", needle); // -> "hello World"

选项2： b

NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"^value:(.+?):value$" options:0 error:nil];
NSTextCheckingResult *match = [regex firstMatchInString:haystack options:NSAnchoredSearch range:NSMakeRange(0, haystack.length)];
NSRange needleRange = [match rangeAtIndex: 1];
NSString *needle = [haystack substringWithRange:needleRange];

这可能是一个有点超过顶部你的相当微不足道的情况。

This one might be a bit over the top for your rather trivial case though.

选项3：

NSString *needle = [haystack componentsSeparatedByString:@":"][1];

这会在分割时创建三个临时字符串和数组。

This one creates three temporary strings and an array while splitting.

所有代码段假定搜索的内容实际上包含在字符串中。

All snippets assume that what's searched for is actually contained in the string.

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