iOS 字符串中多个子符串的替换方法

//在字符串sting1 中将所有string2  替换成string3

-(NSString *)stringByReplacingCharactersInRangeString:(NSString *)string1 andString:(NSString *)string2 andorString:(NSString *)string3{
    
    NSUInteger cnt = 0, length = [string1 length];
    NSRange range = NSMakeRange(0, length);
    while(range.location != NSNotFound)
    {
        range = [string1 rangeOfString: string2 options:0 range:range];
        
        if(range.location != NSNotFound)
        {
            string1 = [string1 stringByReplacingCharactersInRange:range withString:string3];
            range = NSMakeRange(range.location + range.length, length - (range.location + range.length));
            cnt++;
        }
    }
    return string1;
}