一. iOS Base64URL編碼：
java中，在進(jìn)行base64編碼時(shí)會(huì)看到類似如下代碼：

 String result = Base64.encodeToString(bytedata, Base64.URL_SAFE | Base64.NO_WRAP |  Base64.NO_PADDING)；

其中參數(shù)的含義是：

 URL_SAFE：安全的URL編碼，base64轉(zhuǎn)碼過程中會(huì)生成“+”，“/”，“=”這些會(huì)被URL進(jìn)行轉(zhuǎn)碼的特殊字符，導(dǎo)致前后臺(tái)數(shù)據(jù)不同，所以需要將這些字符替代為URL不會(huì)進(jìn)行轉(zhuǎn)碼的字符，保證數(shù)據(jù)同步；
        "-" -> "+"
        "_" -> "/"
    NO_WRAP：不換行
    NO_PADDING："="號(hào)補(bǔ)齊去除，base64會(huì)對(duì)字符進(jìn)行串長(zhǎng)度余4的"="的補(bǔ)位，需去除"="。

這些功能都是android.utils.Base64中自帶的
在iOS中沒有，所以我們只能自己動(dòng)手了～

Swift代碼：

//MARK: Data轉(zhuǎn)Base64URL加密
internal class func convertByte(bytedata:Data?) -> String {
    guard let bytedata = bytedata else {
        return ""
    }
    // data數(shù)據(jù)進(jìn)行base64加密
    guard let result = bytedata.base64EncodedString() else {
        return ""
    }
    // %替換為_
    let result4 = result.replacingOccurrences(of: "%", with: "_")
    // =替換為空
    let result1 = result4.replacingOccurrences(of: "=", with: "")
    // +替換為—
    let result2 = result1.replacingOccurrences(of: "+", with: "-")
    // /替換為_
    let result3 = result2.replacingOccurrences(of: "/", with: "_")
    return result3
}
//MARK: 后臺(tái)反回的base64字符串轉(zhuǎn)為data
internal class func convertBase64URL(base64:String?) -> Data? {
    guard let base64 = base64 else {
        return nil
    }
    // -替換為+
    let base64Str = base64.replacingOccurrences(of: "-", with: "+")
    // _替換為/
    let base64Str2 = base64Str.replacingOccurrences(of: "_", with: "/")
    var base64Str3 = ""
    // =號(hào)補(bǔ)全
    let mod4 = base64Str.count % 4
    if mod4 > 0 {
        let appStr = ("====" as NSString).substring(to: (4 - mod4))
        base64Str3 = base64Str2 + appStr
    }
    // base64Str轉(zhuǎn)data并進(jìn)行Base64Decoding
    return Data(base64Encoded: base64Str3, options: Data.Base64DecodingOptions.init(rawValue: 0))
}

OC:

//MARK: 將saveBase64編碼中的"-"，"_"字符串轉(zhuǎn)換成"+"，"/"，字符串長(zhǎng)度余4倍的位補(bǔ)"="
+(NSData*)safeUrlBase64Decode:(NSString*)safeUrlbase64Str
{
            // '-' -> '+'
            // '_' -> '/'
            // 不足4倍長(zhǎng)度，補(bǔ)'='
            NSMutableString * base64Str = [[NSMutableString alloc]initWithString:safeUrlbase64Str];
            base64Str = (NSMutableString * )[base64Str stringByReplacingOccurrencesOfString:@"-" withString:@"+"];
            base64Str = (NSMutableString * )[base64Str stringByReplacingOccurrencesOfString:@"_" withString:@"/"];
            NSInteger mod4 = base64Str.length % 4;
            if(mod4 > 0)
                    [base64Str appendString:[@"====" substringToIndex:(4-mod4)]];
            NSLog(@"Base64原文：%@", base64Str);
            return [GTMBase64 decodeData:[base64Str dataUsingEncoding:NSUTF8StringEncoding]];
            
}

//MARK: 因?yàn)锽ase64編碼中包含有+,/,=這些不安全的URL字符串，所以要進(jìn)行換字符
+(NSString*)safeUrlBase64Encode:(NSData*)data
{
            // '+' -> '-'
            // '/' -> '_'
            // '=' -> ''
            NSString * base64Str = [GTMBase64 stringByEncodingData:data];
            NSMutableString * safeBase64Str = [[NSMutableString alloc]initWithString:base64Str];
            safeBase64Str = (NSMutableString * )[safeBase64Str stringByReplacingOccurrencesOfString:@"+" withString:@"-"];
            safeBase64Str = (NSMutableString * )[safeBase64Str stringByReplacingOccurrencesOfString:@"/" withString:@"_"];
            safeBase64Str = (NSMutableString * )[safeBase64Str stringByReplacingOccurrencesOfString:@"=" withString:@""];
            NSLog(@"safeBase64編碼：%@", safeBase64Str);
            return safeBase64Str;
}