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（1） 因为url支持26个英文字母、数字和少数几个特殊字符，因此，对于url中包含非标准url的字符时（比如有汉字时），就需要对其进行编码。iOS中提供了函数stringByAddingPercentEscapesUsingEncoding对中文和一些特殊字符进行编码，但是stringByAddingPercentEscapesUsingEncoding的功能并不完善，对一些较为特殊的字符无效。而对这些字符则可以使用CFURLCreateStringByteAddingPercentEscapes函数，
1 NSString *str = [NSString stringWithUTF8String:surl.c_str()];
2 str = @”http://218.21.213.10/MobileOA/TIFF/鄂安办发45号关于下达2012年全市安全生产相对控制指标的通知1.jpg”;
3 str = [str stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
（2）
stringByAddingPercentEscapesUsingEncoding用与将Unicode字符转换成有百分号的形式。
stringByReplacingPercentEscapesUsingEncoding:将百分号形式转换成Unicode形式
例子:
NSString *rawText = @”One Broadway, Cambridge, MA”;
NSString *encodedText = [rawText stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSLog(@”Encoded text: %@”, encodedText);
NSString *decodedText = [encodedText stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSLog(@”Original text: %@”, decodedText);
输出:
Encoded text: One%20Broadway,%20Cambridge,%20MA
Original text: One Broadway, Cambridge, MA
＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊
stringByAddingPercentEscapesUsingEncoding对中文和一些特殊字符进行编码，但是stringByAddingPercentEscapesUsingEncoding的功能并不完善，对一些像& ／等特殊的字符无效。而对这些字符则可以使用CFURLCreateStringByteAddingPercentEscapes函数，
例子：
// Encode a string to embed in an URL.
NSString* encodeToPercentEscapeString(NSString *string) {
return (NSString *)
CFURLCreateStringByAddingPercentEscapes(NULL,
(CFStringRef) string,
NULL,
(CFStringRef) @”!*’();:@&=+$,/?%#[]”,
kCFStringEncodingUTF8);
}
// Decode a percent escape encoded string.
NSString* decodeFromPercentEscapeString(NSString *string) {
return (NSString *)
CFURLCreateStringByReplacingPercentEscapesUsingEncoding(NULL,
(CFStringRef) string,
CFSTR(“”),
kCFStringEncodingUTF8);
}
int main (int argc, const char * argv[]) {
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
NSString *rawText = @”Bed Bath & Beyond - URL=http://www.bedbathandbeyond.com/“;
NSString *encodedText = encodeToPercentEscapeString(rawText);
NSLog(@”Encoded text: %@”, encodedText);
NSString *decodedText = decodeFromPercentEscapeString(encodedText);
NSLog(@”Original text: %@”, decodedText);
[pool drain];
return 0;
}
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