//编码
NSData *nsdata = [@"http://www.baidu.com"
dataUsingEncoding:NSUTF8StringEncoding];
// Get NSString from NSData object in Base64
NSString *base64Encoded = [nsdata base64EncodedStringWithOptions:0];
// Print the Base64 encoded string
NSLog(@"Encoded: %@", base64Encoded);
// 解码
// NSData from the Base64 encoded str
NSData *nsdataFromBase64String = [[NSData alloc]
initWithBase64EncodedString:base64Encoded options:0];
// Decoded NSString from the NSData
NSString *base64Decoded = [[NSString alloc]
initWithData:nsdataFromBase64String encoding:NSUTF8StringEncoding];
NSLog(@"Decoded: %@", base64Decoded);
iOS中对字符串进行UTF-8编码：输出str字符串的UTF-8格式
[str stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
解码：把str字符串以UTF-8规则进行解码
[str stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
