iOS开发进制转换

1、十进制转换为二进制

/**
十进制转换为二进制
@param decimal 十进制数
@return 二进制数
*/
+ (NSString *)getBinaryByDecimal:(NSInteger)decimal {

　　NSString *binary = @"";
　　while (decimal) {
　　　　binary = [[NSString stringWithFormat:@"%ld", decimal % 2] stringByAppendingString:binary];
　　　　if (decimal / 2 < 1) {
　　　　　　break;
　　　　}
　　　　decimal = decimal / 2 ;
　　　　}

　　if (binary.length % 4 != 0) {
　　　　NSMutableString *mStr = [[NSMutableString alloc]init];
　　　　for (int i = 0; i < 4 - binary.length % 4; i++) {
　　　　　　[mStr appendString:@"0"];
　　　　}
　　　　binary = [mStr stringByAppendingString:binary];
　　}
　　return binary;
}

 

2、十进制转换为十六进制

/**
 十进制转换十六进制
  
 @param decimal 十进制数
 @return 十六进制数
 */
+ (NSString *)getHexByDecimal:(NSInteger)decimal {
    
    NSString *hex =@"";
    NSString *letter;
    NSInteger number;
    for (int i = 0; i<9; i++) {
        
        number = decimal % 16;
        decimal = decimal / 16;
        switch (number) {
                
            case 10:
                letter =@"A"; break;
            case 11:
                letter =@"B"; break;
            case 12:
                letter =@"C"; break;
            case 13:
                letter =@"D"; break;
            case 14:
                letter =@"E"; break;
            case 15:
                letter =@"F"; break;
            default:
                letter = [NSString stringWithFormat:@"%ld", number];
        }
        hex = [letter stringByAppendingString:hex];
        if (decimal == 0) {
            break;
        }
    }
    return hex;
}

3、 二进制转换为十六进制

/**
 二进制转换成十六进制
   
 @param binary 二进制数
 @return 十六进制数
 */
+ (NSString *)getHexByBinary:(NSString *)binary {
    
    NSMutableDictionary *binaryDic = [[NSMutableDictionary alloc] initWithCapacity:16];
    [binaryDic setObject:@"0" forKey:@"0000"];
    [binaryDic setObject:@"1" forKey:@"0001"];
    [binaryDic setObject:@"2" forKey:@"0010"];
    [binaryDic setObject:@"3" forKey:@"0011"];
    [binaryDic setObject:@"4" forKey:@"0100"];
    [binaryDic setObject:@"5" forKey:@"0101"];
    [binaryDic setObject:@"6" forKey:@"0110"];
    [binaryDic setObject:@"7" forKey:@"0111"];
    [binaryDic setObject:@"8" forKey:@"1000"];
    [binaryDic setObject:@"9" forKey:@"1001"];
    [binaryDic setObject:@"A" forKey:@"1010"];
    [binaryDic setObject:@"B" forKey:@"1011"];
    [binaryDic setObject:@"C" forKey:@"1100"];
    [binaryDic setObject:@"D" forKey:@"1101"];
    [binaryDic setObject:@"E" forKey:@"1110"];
    [binaryDic setObject:@"F" forKey:@"1111"];
    
    if (binary.length % 4 != 0) {
        
        NSMutableString *mStr = [[NSMutableString alloc]init];;
        for (int i = 0; i < 4 - binary.length % 4; i++) {
            
            [mStr appendString:@"0"];
        }
        binary = [mStr stringByAppendingString:binary];
    }
    NSString *hex = @"";
    for (int i=0; i<binary.length; i+=4) {
        
        NSString *key = [binary substringWithRange:NSMakeRange(i, 4)];
        NSString *value = [binaryDic objectForKey:key];
        if (value) {
            
            hex = [hex stringByAppendingString:value];
        }
    }
    return hex;
}