NSString自帶的的方法ＵＲＬ　ｅｎｃｏｄｉｎｇ的編碼問題

NSString *password = @"Top+Secret. ";
NSString *encoded_normal = [password stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSString *encoded_safer = (NSString *)CFURLCreateStringByAddingPercentEscapes(NULL,  (CFStringRef)password,  NULL,  (CFStringRef)@"!*'();:@&=+$,/?%#[]",  kCFStringEncodingUTF8);
 
// output with %@ otherwise the % escapes cause strange output
NSLog(@"%@", password);
NSLog(@"%@", encoded_normal);
NSLog(@"%@", encoded_safer);

通過輸出情況看，用

stringByAddingPercentEscapesUsingEncoding：方法編碼時，+號沒有編碼，存在不ｅｎｃｏｄｅ的情況

推薦使用

CFURLCreateStringByAddingPercentEscapes（）

下面是一個給ＮＳＳｔｒｉｎｇ添加的類別，來實現ｅｎｃｏｄｅ

#import 
 
@interface NSString (Helpers)
 
// helper functions
- (NSString *) stringByUrlEncoding;
 
@end

#import "NSString+Helpers.h"
 
@implementation NSString (Helpers)
 
#pragma mark Helpers
- (NSString *) stringByUrlEncoding
{
	return (NSString *)CFURLCreateStringByAddingPercentEscapes(NULL,  (CFStringRef)self,  NULL,  (CFStringRef)@"!*'();:@&=+$,/?%#[]",  kCFStringEncodingUTF8);
}