iPhone如何迭代遍历NSString中的子字符串出现次数？

Question

iPhone如何迭代遍历NSString中的子字符串出现次数？

iphonensstring

6

我想在一个NSString中查找所有子字符串的出现位置，并逐个迭代对该NSString进行一些更改。我应该怎么做？

- Luis Andrés García

你的意思是如果你有@"abcabcabcabcabcabc"，你想要遍历所有的@"abc"吗？ - mattjgalloway

5个回答

7

我建议您采用类似以下的内容：

我会选择这样的一种方案：

// Setup what you're searching and what you want to find
NSString *string = @"abcabcabcabc";
NSString *toFind = @"abc";

// Initialise the searching range to the whole string
NSRange searchRange = NSMakeRange(0, [string length]);
do {
    // Search for next occurrence
    NSRange range = [string rangeOfString:toFind options:0 range:searchRange];
    if (range.location != NSNotFound) {
        // If found, range contains the range of the current iteration

        // NOW DO SOMETHING WITH THE STRING / RANGE

        // Reset search range for next attempt to start after the current found range
        searchRange.location = range.location + range.length;
        searchRange.length = [string length] - searchRange.location;
    } else {
        // If we didn't find it, we have no more occurrences
        break;
    }
} while (1);

- mattjgalloway

这太复杂了，有一个方法可以解决：

- (void)enumerateSubstringsInRange:(NSRange)range options:(NSStringEnumerationOptions)opts usingBlock:(void (^)(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop))block

。 - calimarkus

在搜索了很多之后非常有帮助。谢谢。+1 - Prerna chavan

Matt的方法允许您更改字符串，因为它没有被枚举。 - Stephen J

5

如果你想进行更改，可以使用以下方法：

- (NSString *)stringByReplacingOccurrencesOfString:(NSString *)target withString:(NSString *)replacement

但如果这不符合你的需求，请尝试使用以下方法：

- (void)enumerateSubstringsInRange:(NSRange)range options:(NSStringEnumerationOptions)opts usingBlock:(void (^)(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop))block

- calimarkus

请查看 HelmiB 所指出的文档。 - calimarkus

1

你可能想要查看NSString类文档。

查找字符和子字符串

– rangeOfCharacterFromSet:
– rangeOfCharacterFromSet:options:
– rangeOfCharacterFromSet:options:range:
– rangeOfString:
– rangeOfString:options:
– rangeOfString:options:range:
– rangeOfString:options:range:locale:
– enumerateLinesUsingBlock:
– enumerateSubstringsInRange:options:usingBlock:

字符串分割

– componentsSeparatedByString:
– componentsSeparatedByCharactersInSet:
– stringByTrimmingCharactersInSet:
– substringFromIndex:
– substringWithRange:
– substringToIndex:

- HelmiB

0

在 @TheEye 的 answer 上进行扩展，我想到了这个：

@interface NSString (EnumerateOccurancesOfString)

- (void)enumerateOccurancesOfString:(NSString *)string usingBlock:(void (^)(NSRange substringRange, BOOL *stop))block;

@end

-

@implementation NSString (EnumerateOccurancesOfString)

- (void)enumerateOccurancesOfString:(NSString *)string usingBlock:(void (^)(NSRange range, BOOL * _Nonnull stop))block {

    NSParameterAssert(block);

    NSRange range = [self localizedStandardRangeOfString:string];

    if (range.location == NSNotFound) return;


    // Iterate all occurances of 'string'
    while (range.location != NSNotFound)
    {
        BOOL stop = NO;

        block(range, &stop);

        if (stop) {
            break;
        }

        // Continue the iteration
        NSRange nextRange = NSMakeRange(range.location + 1, self.length - range.location - 1);
        range = [self rangeOfString:string options:(NSStringCompareOptions)0 range:nextRange locale:[NSLocale currentLocale]]; // Will this sometimes conflict with the initial range obtained with -localizedStandardRangeOfString:?
    }
}

@end

- Stian Høiland

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- TheEye · Accepted Answer

怎么样？

// find first occurrence of search string in source string
NSRange range = [sourceString rangeOfString:@"searchString"];
while(range.location != NSNotFound)
{
    // build a new string with your changed values

    range = [sourceString rangeOfString:@"searchString" options:0 range:NSMakeRange(range.location + 1, [sourceString length] - range.location - 1)];
}

或者只需

[sourceString stringByReplacingOccurrencesOfString:searchString withString:targetString];

如果你想要在源字符串中将搜索字符串的值随处更改为相同的值。