URL编码是一种常见的编码方式，作用不多说，直接上代码。
URL编码：
- (NSString *)URLEncodedString {// CharactersToBeEscaped = @":/?&=;+!@#$()~',*";// CharactersToLeaveUnescaped = @"[].";NSString *unencodedString = self;NSString *encodedString = (NSString *)CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,(CFStringRef)unencodedString,NULL,(CFStringRef)@"!*'();:@&=+$,/?%#[]",kCFStringEncodingUTF8));return encodedString;}
URL解码：
- (NSString *)URLDecodedString {NSString *result = [(NSString *)self stringByReplacingOccurrencesOfString:@"+" withString:@" "];return [result stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];}
建议这两个方法放在NSString的分类中，并且声明为实例方法，这样可以直接用NSString的对象去调用。
- 调用示例
NSString * string = @"zhansan啦啦啦啦1234567";NSString * urlEncode = [string URLEncodedString];NSString * urlDecode = [string URLDecodedString];NSLog(@"urlEncode == %@",urlEncode);NSLog(@"urlDecode == %@",urlDecode);
打印结果：
urlEncode == zhansan%E5%95%A6%E5%95%A6%E5%95%A6%E5%95%A61234567urlDecode == zhansan啦啦啦啦1234567
