stringByAddingPercentEscapesUsingEncoding: 和stringByReplacingPercentEscapesUsingEncoding:的不同

（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;

}