ios基本编码格式转换UTF8

iOS中编码转化

1.UTF-8转化

NSString *data = @"你好，北京！";

//转换成UTF-8

NSString *dataUTF8 = [data stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

NSLog(@"%@",dataUTF8);

//UTF-8转GBK,将UTF8代码替换，官方解释如下。

//Replaces all percent escapes with the matching characters as determined by the given encoding. Returns nil if the transformation is not possible (i.e. the percent escapes give a byte sequence not legal in the given encoding). See CFURLCreateStringByReplacingPercentEscapes in CFURL.h for more complex transformations

NSString *dataGBK = [dataUTF8 stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

NSLog(@"%@",dataGBK);

在Xcode4.2中执行结果如下：

将上述方法封装，如下：

 1 //Unicode转UTF-8
 2 
 3  
 4 
 5 + (NSString *)encodeToPercentEscapeString: (NSString *) input  
 6 
 7 {  
 8 
 9     // Encode all the reserved characters, per RFC 3986  
10 
11     // (<http://www.ietf.org/rfc/rfc3986.txt>)  
12 
13     NSString *outputStr = (NSString *)   
14 
15     CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,  
16 
17                                             (CFStringRef)input,  
18 
19                                             NULL,  
20 
21                                             (CFStringRef)@"!*'();:@&=+$,/?%#[]",  
22 
23                                             kCFStringEncodingUTF8);  
24 
25     return outputStr;  
26 
27 }  
28 
29  
30 
31 + (NSString *)decodeFromPercentEscapeString: (NSString *) input  
32 
33 {  
34 
35     NSMutableString *outputStr = [NSMutableString stringWithString:input];  
36 
37     [outputStr replaceOccurrencesOfString:@"+"  
38 
39                                withString:@" "  
40 
41                                   options:NSLiteralSearch  
42 
43                                     range:NSMakeRange(0, [outputStr length])];  
44 
45     
46 
47     return [outputStr stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];  
48 
49 }

2.UTF-8和Unicode转化

 1 //Unicode转UTF-8
 2 
 3 + (NSString*) replaceUnicode:(NSString*)aUnicodeString
 4 
 5 {
 6 
 7     NSString *tempStr1 = [aUnicodeString stringByReplacingOccurrencesOfString:@"\u" withString:@"\U"];  
 8 
 9     NSString *tempStr2 = [tempStr1 stringByReplacingOccurrencesOfString:@""" withString:@"\""];  
10 
11     NSString *tempStr3 = [[@""" stringByAppendingString:tempStr2] stringByAppendingString:@"""];  
12 
13     NSData *tempData = [tempStr3 dataUsingEncoding:NSUTF8StringEncoding];  
14 
15     NSString* returnStr = [NSPropertyListSerialization propertyListFromData:tempData  
16 
17                                                            mutabilityOption:NSPropertyListImmutable   
18 
19                                                                      format:NULL  
20 
21                                                            errorDescription:NULL];  
22 
23     
24 
25     return [returnStr stringByReplacingOccurrencesOfString:@"\r\n" withString:@"
"]; 
26 
27 }
28 
29  
30 
31  
32 
33 +(NSString *) utf8ToUnicode:(NSString *)string
34 
35 {
36 
37     NSUInteger length = [string length];
38 
39     NSMutableString *s = [NSMutableString stringWithCapacity:0];
40 
41     for (int i = 0;i < length; i++) 
42 
43     {
44 
45         unichar _char = [string characterAtIndex:i];
46 
47         //判断是否为英文和数字
48 
49         if (_char <= '9' && _char >= '0') 
50 
51         {
52 
53             [s appendFormat:@"%@",[string substringWithRange:NSMakeRange(i, 1)]];
54 
55         }
56 
57         else if(_char >= 'a' && _char <= 'z')
58 
59         {
60 
61             [s appendFormat:@"%@",[string substringWithRange:NSMakeRange(i, 1)]];
62 
63             
64 
65         }
66 
67         else if(_char >= 'A' && _char <= 'Z')
68 
69         {
70 
71             [s appendFormat:@"%@",[string substringWithRange:NSMakeRange(i, 1)]];
72 
73             
75         }
76 
77         else
78 
79         {
80 
81             [s appendFormat:@"\u%x",[string characterAtIndex:i]];
82 
83         }
84 
85     }
86 
87     return s;
88 
89 }

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原文地址：https://www.cnblogs.com/csdnIOS/p/4195354.html