【IOS开发基础系列】数据编解码专题

1 Base64

1.1 在iOS7中系统提供了base64的转码方式

示例如下：

NSData* originData = [originStr dataUsingEncoding: NSASCIIStringEncoding];
NSString* encodeResult = [originData base64EncodedStringWithOptions: NSDataBase64EncodingEndLineWithLineFeed];
NSLog(@"encodeResult:%@",encodeResult);
NSData* decodeData = [[NSData alloc] initWithBase64EncodedString: encodeResult options:0];
NSString* decodeStr = [[NSString alloc] initWithData: decodeData encoding: NSASCIIStringEncoding];

1.2 iOS使用开源库GTMBase64转码

/**
*GTM 转码
*/
- (void)GTMEncodeTest
{
    NSString* originStr = @"Man";
    NSString* encodeResult = nil;
    NSData* originData = [originStr dataUsingEncoding: NSUTF8StringEncoding];
    NSData* encodeData = [GTMBase64 encodeData: originData];
    encodeResult = [[NSString alloc] initWithData: encodeData encoding: NSUTF8StringEncoding];
    NSLog(@"%@",encodeResult);
}
/**
* GTM 解码
*/
- (void)GMTDecodeTest
{
   NSString* encodeStr = @"TWFu";
    NSString* decodeResult = nil;
    NSData* encodeData = [encodeStr dataUsingEncoding: NSUTF8StringEncoding];
    NSData* decodeData = [GTMBase64 decodeData: encodeData];
    decodeResult = [[NSString alloc] initWithData: decodeData encoding: NSUTF8StringEncoding];
    NSLog(@"%@",decodeResult);
}

2 JSON

2.1 JSON与NSDictionary互相转换

2.1.1 NSDictionary转换为NSString

- (NSString*) DataTOjsonString: (id)object
{
    NSString*jsonString = nil;
    NSError *error;
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject: object options: NSJSONWritingPrettyPrinted  error: &error];
// Pass 0 if you don't care about the readability of the generated string
    if (! jsonData) {
       NSLog(@"Got an error: %@", error);
    }else{
        jsonString= [[NSString alloc] initWithData: jsonData encoding: NSUTF8StringEncoding];
    }
    return jsonString;
}

注意：

此时转换成的字符串中，每个键值对之间会预留一个回车换行符，导致http传输时会出错，因此如果要用于http网络传输时，需要手动将回车符替换掉！！！

jsonString = [jsonString stringByReplacingOccurrencesOfString: @"\n" withString:@""];

2.1.2 将JSON串转化为NSDictionary或NSArray

// 将JSON串转化为字典或者数组
- (id)toArrayOrNSDictionary: (NSData*)jsonData{
    NSError *error = nil;
    id jsonObject = [NSJSONSerialization JSONObjectWithData: jsonData options: NSJSONReadingAllowFragments error: &error];
    if (jsonObject != nil && error == nil){
        return jsonObject;
    }else{
        // 解析错误
         return nil;
    }
}

3 参考链接

iOS Base64转码（使用ios7系统自带编码库 和GMTBase64两种方式）

http://www.2cto.com/kf/201405/297303.html

[译]iOS7:使用Base64编解码NSData和NSString对象

http://itony.me/488.html

iOS:Terminating app due to uncaught exception'NSInvalidArgumentException', reason: 'Invalid type in JSON write(_NSInlineData)'

http://stackoverflow.com/questions/24984098/iosterminating-app-due-to-uncaught-exception-nsinvalidargumentexception-reas

NSDictionary to jsonString ||对象转json格式

http://www.cnblogs.com/qingjoin/p/3437036.html

将NSString转换成UTF8编码的NSString

http://blog.csdn.net/a6472953/article/details/8163016

NSJSONSerialization-JSON数据与NSDictionary和NSArray之间的转化

http://blog.csdn.net/xyxjn/article/details/17224733

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作者：junbaozi 

原文：https://blog.csdn.net/junbaozi/article/details/79491868