新浪微博mid与url互转

#pragma mark - 新浪微博mid与url互转
-(NSArray*)str62keys
{
    return @[@"0",@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",
             @"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",@"i",@"j",@"k",@"l",@"m",@"n",@"o",@"p",@"q",@"r",@"s",@"t",@"u",@"v",@"w",@"x",@"y",@"z",
             @"A",@"B",@"C",@"D",@"E",@"F",@"G",@"H",@"I",@"J",@"K",@"L",@"M",@"N",@"O",@"P",@"Q",@"R",@"S",@"T",@"U",@"V",@"W",@"X",@"Y",@"Z"];
}
/**
 * 62进制值转换为10进制
 * @param {NSString} str62 62进制值
 * @return {NSString} 10进制值
 */
-(NSInteger)str62to10:(NSString*)str62
{
    NSInteger i10 = 0;
	for (int i = 0; i < [str62 length]; i++)
	{
        
		NSInteger n = str62.length - i - 1;
        NSRange range=NSMakeRange(n, 1);
		NSString* s = [str62 substringWithRange:range];
		i10 += [[self str62keys]indexOfObject:s] * pow(62, i);
	}
	return i10;
}
/**
 * 10进制值转换为62进制
 * @param {NSString} int10 10进制值
 * @return {NSString} 62进制值
 */
-(NSString*)int10to62:(NSInteger)int10
{
    NSMutableString* s62 = [NSMutableString stringWithCapacity:200];
    NSInteger r=0;
    while (int10!=0 && [s62 length]<100) {
        r=int10%62;
        NSString* temp=[self str62keys][r];
        [s62 insertString:temp atIndex:0];
        int10 = floor(int10 / 62);
    }
    return s62;
}

/**
 * URL字符转换为mid
 * @param {NSString} url 微博URL字符，如 "wr4mOFqpbO"
 * @return {NSString} 微博mid，如 "201110410216293360"
 */
-(NSString*)url2mid:(NSString*)url
{
    NSMutableString* mid= [NSMutableString stringWithCapacity:200];
    for (int i=[url length]-4; i> -4; i=i-4) { //从最后往前以4字节为一组读取URL字符
        int offset1 = i < 0 ? 0 : i ;
        int length =  i< 0? i+4 : 4;

        NSMutableString* str= [NSMutableString stringWithCapacity:200];
        [str setString:[url substringWithRange:NSMakeRange(offset1, length)]];
        [str setString:[NSString stringWithFormat:@"%d",[self str62to10:str]]];
        
        if (offset1 > 0) {//若不是第一组，则不足7位补0
            while ([str length]<7) {
                [str insertString:@"0" atIndex:0];
            }
        }
        [mid insertString:str atIndex:0];
    }
    return mid;
}
/**
 * mid转换为URL字符
 * @param {NSString} mid 微博mid，如 "201110410216293360"
 * @return {NSString} 微博URL字符，如 "wr4mOFqpbO"
 */
-(NSString*) mid2url:(NSString*)mid
{
    if (![mid length]) {
        return mid;
    }
    NSMutableString* url= [NSMutableString stringWithCapacity:200];
    for (int i= [mid length]-7;i>-7; i=i-7) {//从最后往前以7字节为一组读取mid
        int offset1 = i<0?0:i;
        int length=i<0?i+7:7;
        
        NSString* num = [mid substringWithRange:NSMakeRange(offset1, length)];
        NSString* temp=[self int10to62:[num intValue]];
        [url insertString:temp atIndex:0];
    }
    return url;
}

-(NSString*)getWeiboURLWithMid:(NSString*)mid user:(NSString*)uid
{
    //http://weibo.com/1962310741/ACzePqDqV
    
    NSString* midUrl=[self mid2url:mid];
    NSString* url=@"http://weibo.com";
    if ([midUrl length]&& [uid length]) {
        url = [NSString stringWithFormat:@"http://weibo.com/%@/%@",uid,midUrl];
    }
    return url;
}