如何从NSString的右端删除空格? [英] How to remove whitespace from right end of NSString?

问题描述

这会删除字符串两端的空白:

This removes white space from both ends of a string:

NSString *newString = [oldString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

如何从字符串的右端删除空格?

How do I remove white space from just the right end of a string?

更新:接受的代码答案现在是 SSToolkit的一部分.是的！

推荐答案

以@Regexident& @Max，我想出了以下方法:

Building on the answers by @Regexident & @Max, I came up with the following methods:

@implementation NSString (SSToolkitAdditions)

#pragma mark Trimming Methods

- (NSString *)stringByTrimmingLeadingCharactersInSet:(NSCharacterSet *)characterSet {
    NSRange rangeOfFirstWantedCharacter = [self rangeOfCharacterFromSet:[characterSet invertedSet]];
    if (rangeOfFirstWantedCharacter.location == NSNotFound) {
        return @"";
    }
    return [self substringFromIndex:rangeOfFirstWantedCharacter.location];
}

- (NSString *)stringByTrimmingLeadingWhitespaceAndNewlineCharacters {
    return [self stringByTrimmingLeadingCharactersInSet:
            [NSCharacterSet whitespaceAndNewlineCharacterSet]];
}

- (NSString *)stringByTrimmingTrailingCharactersInSet:(NSCharacterSet *)characterSet {
    NSRange rangeOfLastWantedCharacter = [self rangeOfCharacterFromSet:[characterSet invertedSet]
                                                               options:NSBackwardsSearch];
    if (rangeOfLastWantedCharacter.location == NSNotFound) {
        return @"";
    }
    return [self substringToIndex:rangeOfLastWantedCharacter.location+1]; // non-inclusive
}

- (NSString *)stringByTrimmingTrailingWhitespaceAndNewlineCharacters {
    return [self stringByTrimmingTrailingCharactersInSet:
            [NSCharacterSet whitespaceAndNewlineCharacterSet]];
}

@end

这是GHUnit测试，所有测试当然都通过了:

And here are the GHUnit tests, which all pass of course:

@interface StringCategoryTest : GHTestCase
@end

@implementation StringCategoryTest

- (void)testStringByTrimmingLeadingCharactersInSet {
    NSCharacterSet *letterCharSet = [NSCharacterSet letterCharacterSet];
    GHAssertEqualObjects([@"zip90210zip" stringByTrimmingLeadingCharactersInSet:letterCharSet], @"90210zip", nil);
}

- (void)testStringByTrimmingLeadingWhitespaceAndNewlineCharacters {
    GHAssertEqualObjects([@"" stringByTrimmingLeadingWhitespaceAndNewlineCharacters], @"", nil);
    GHAssertEqualObjects([@"\n \n " stringByTrimmingLeadingWhitespaceAndNewlineCharacters], @"", nil);
    GHAssertEqualObjects([@"\n hello \n" stringByTrimmingLeadingWhitespaceAndNewlineCharacters], @"hello \n", nil);
}

- (void)testStringByTrimmingTrailingCharactersInSet {
    NSCharacterSet *letterCharSet = [NSCharacterSet letterCharacterSet];
    GHAssertEqualObjects([@"zip90210zip" stringByTrimmingTrailingCharactersInSet:letterCharSet], @"zip90210", nil);
}

- (void)testStringByTrimmingTrailingWhitespaceAndNewlineCharacters {
    GHAssertEqualObjects([@"" stringByTrimmingLeadingWhitespaceAndNewlineCharacters], @"", nil);
    GHAssertEqualObjects([@"\n \n " stringByTrimmingLeadingWhitespaceAndNewlineCharacters], @"", nil);
    GHAssertEqualObjects([@"\n hello \n" stringByTrimmingTrailingWhitespaceAndNewlineCharacters], @"\n hello", nil);
}

@end

我向 SSToolkit 提交了GitHub提取请求，并添加了这些方法.

I submitted a GitHub pull request to SSToolkit with these methods added.

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