Objective-c iPhone百分比编码一个字符串？ [英] Objective-c iPhone percent encode a string?

问题描述

我想获取这些特定字母的百分比编码字符串，如何在objective-c中执行此操作？

I would like to get the percent encoded string for these specific letters, how to do that in objective-c?

Reserved characters after percent-encoding
!   *   '   (   )   ;   :   @   &   =   +   $   ,   /   ?   #   [   ]
%21 %2A %27 %28 %29 %3B %3A %40 %26 %3D %2B %24 %2C %2F %3F %23 %5B %5D

百分比-encoding wiki

请使用此字符串进行测试，看看它是否有效：

Please test with this string and see if it do work:

myURL = @"someurl/somecontent"

我想要字符串看起来像：

I would like the string to look like:

myEncodedURL = @"someurl%2Fsomecontent"

我尝试使用 stringByAddingPercentEscapesUsingEncoding：NSASCIIStringEncoding 但它不起作用，结果仍然与原始字符串。请建议。

I tried with the stringByAddingPercentEscapesUsingEncoding: NSASCIIStringEncoding already but it does not work, the result is still the same as the original string. Please advice.

推荐答案

我发现 stringByAddingPercentEscapesUsingEncoding：和 CFURLCreateStringByAddingPercentEscapes（）不足。 NSString 方法错过了很多字符，CF函数只允许您说出要转义的（特定）字符。正确的规范是转义除了一小组之外的所有字符。

I've found that both stringByAddingPercentEscapesUsingEncoding: and CFURLCreateStringByAddingPercentEscapes() are inadequate. The NSString method misses quite a few characters, and the CF function only lets you say which (specific) characters you want to escape. The proper specification is to escape all characters except a small set.

为了解决这个问题，我创建了一个 NSString 类别正确编码字符串的方法。除了 [a-zA-Z0-9。-_~] 之外，它将对所有内容进行编码，并将空格编码为 + （根据此规范）。它还将正确处理编码unicode字符。

To fix this, I created an NSString category method to properly encode a string. It will percent encoding everything EXCEPT [a-zA-Z0-9.-_~] and will also encode spaces as + (according to this specification). It will also properly handle encoding unicode characters.

- (NSString *) URLEncodedString_ch {
    NSMutableString * output = [NSMutableString string];
    const unsigned char * source = (const unsigned char *)[self UTF8String];
    int sourceLen = strlen((const char *)source);
    for (int i = 0; i < sourceLen; ++i) {
        const unsigned char thisChar = source[i];
        if (thisChar == ' '){
            [output appendString:@"+"];
        } else if (thisChar == '.' || thisChar == '-' || thisChar == '_' || thisChar == '~' || 
                   (thisChar >= 'a' && thisChar <= 'z') ||
                   (thisChar >= 'A' && thisChar <= 'Z') ||
                   (thisChar >= '0' && thisChar <= '9')) {
            [output appendFormat:@"%c", thisChar];
        } else {
            [output appendFormat:@"%%%02X", thisChar];
        }
    }
    return output;
}

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