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:@"\n"];
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 }