ios - 对 url 字符串进行编码

Question

我正在尝试使用 Objective-c 编码 url 字符串

// 1. Get string
char res = ((char)(400));
NSString *unencodedString = [NSString stringWithFormat:@"%c",res];

// 2. Encode string
static NSString *escape = @":/?&=;+!@#$()',*[]";
NSString *result = (__bridge_transfer  NSString *)
CFURLCreateStringByAddingPercentEscapes(
                                        NULL,
                                        (__bridge CFStringRef)unencodedString,
                                        NULL,
                                        (__bridge CFStringRef)escape,
                                        kCFStringEncodingUTF8);
// result = %C2%90

但是结果并不是我所期望的。因为我得到%C6%90使用其他编程语言。

如您所见，Objective-C 结果是 %C2%90 ，但我期望%C6%90 .

我的错误在哪里？我做错了什么吗？

Answer 1

问题是 NSString *unencodedString = [NSString stringWithFormat:@"%c",res] 没有做你认为它做的事情。 char res 不能保存大于 128 的值(unsigned char 为 256)。

char res = ((char)(400));
NSString *unencodedString = [NSString stringWithFormat:@"%c",res];
XCTAssertEqualObjects(unencodedString, @"\xc2\x90", @"");

static NSString *escape = @":/?&=;+!@#$()',*[]";
NSString *result = (__bridge_transfer  NSString *)
CFURLCreateStringByAddingPercentEscapes(
                                        NULL,
                                        (__bridge CFStringRef)unencodedString,
                                        NULL,
                                        (__bridge CFStringRef)escape,
                                        kCFStringEncodingUTF8);

XCTAssertEqualObjects(result, @"%C2%90", @"");

这是一个有效的示例。

NSString *unencodedString = @"Ɛ";

static NSString *escape = @":/?&=;+!@#$()',*[]";
NSString *result = (__bridge_transfer  NSString *)
CFURLCreateStringByAddingPercentEscapes(
                                        NULL,
                                        (__bridge CFStringRef)unencodedString,
                                        NULL,
                                        (__bridge CFStringRef)escape,
                                        kCFStringEncodingUTF8);
XCTAssertEqualObjects(result, @"%C6%90", @"");

---

更新

如果您希望这样的示例正常工作，请使用 unichar 和 -stringWithCharacters:length:。

unichar res = ((unichar)(400));
NSString *unencodedString = [NSString stringWithCharacters:&res length:1];
XCTAssertEqualObjects(unencodedString, @"Ɛ", @"");

static NSString *escape = @":/?&=;+!@#$()',*[]";
NSString *result = (__bridge_transfer  NSString *)
CFURLCreateStringByAddingPercentEscapes(
                                        NULL,
                                        (__bridge CFStringRef)unencodedString,
                                        NULL,
                                        (__bridge CFStringRef)escape,
                                        kCFStringEncodingUTF8);
XCTAssertEqualObjects(result, @"%C6%90", @"");