iOS编码

gbk

NSStringEncoding enc =CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);

utf8

NSUTF8StringEncoding

iso_8891

NSISOLatin1StringEncoding

编码

%2b%2b%2b是url编码，如果是3个代表一个汉字，是Utf8;2个代表汉字，是gbk.

NSString *dataUTF8 = [@"测试"stringByAddingPercentEscapesUsingEncoding:enc];
或者

NSString* test = (__bridge_transferNSString *)CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,
(__bridgeCFStringRef)@"测试", NULL,
(CFStringRef)@"!*'();:@&=+$,/?%#[]",kCFStringEncodingUTF8);

解码

NSString* c = [bstringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

NSString 与 NSData互相转化

NSData* data = [@"haha"dataUsingEncoding:NSUTF8StringEncoding];
NSString* str = [[NSStringalloc]initWithData:dataencoding:NSUTF8StringEncoding];

从Utf8转成gbk

NSString* a = [@"你好"
stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSString* b = [a
stringByReplacingPercentEscapesUsingEncoding:gbk];
或者
NSString* a = [@"你好" stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

NSString* b = [a stringByReplacingPercentEscapesUsingEncoding:gbk];

结果：浣犲ソ

从gbk转成utf8 同理，不过结果 为nil