ios NSString md5 base64 urlEncode isEmail

发现太高深的写不出来了（虽然是从来没写过），总结总结基础的东西吧，让自己以后忘了也能来看看。1.常用功能使用1）初始化NSString *astring = @"This is a String!";                             //固定字符串NSString *str = [NSString stringWithFormat:@"asd%d%@",123,@"ttt"];    //拼组字符串2）截取NSString *str = [@"asd" substringFromIndex:1];                       //从第几位开始截到最后NSString *str1 = [str substringToIndex:1];                           //从开始位置截到第几位NSString *str = [[@"asd" substringFromIndex:1] substringToIndex:1];  //从第几位开始截几个字符3）分解NSArray *array = [@"asd|tes|mmm" componentsSeparatedByString:@"|"];4）查找 NSRange range = [@"12rasd124" rangeOfString:@"asd"]; if (range.location != NSNotFound) {      NSString *str = [@"12rasd124" substringWithRange:range]; }5）替换NSString *str = [@"asdasd" stringByReplacingOccurrencesOfString:@"asd" withString:@"ok"];6）路径相关[filepath lastPathComponent];                 //获得文件名[filepath pathExtension];                     //获得文件扩展名[filtpaht stringByDeletingLastPathComponent]; //获得文件的所在文件夹路径[filtpath stringByDeletingPathExtension];     //获得去除扩展名的文件路径7）字符串是否为空if (str.lenght > 0) //不管str是不是nil都可以这么判断8）字符串比较if ([@"asd" isEqualToString:@"asd"]) {}9）字符串比大小    NSString *stra = @"asd";    NSString *strb = @"dfs";    NSComparisonResult result = [stra compare:strb];    if (result == NSOrderedSame) {    } else if (result == NSOrderedAscending) {    } else {    }2.常用扩展功能(类别扩展)1）md5- (NSString *)md5HexDigest{    const char* str = [self UTF8String];    unsigned char result[CC_MD5_DIGEST_LENGTH];    CC_MD5(str, strlen(str), result);    NSMutableString *ret = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH];    for(int i = 0; i<CC_MD5_DIGEST_LENGTH; i++) {        [ret appendFormat:@"%02X",result[i]];    }    return ret;}2）urlEncode- (NSString *)stringEncode {    NSString *encodedString = (NSString *)CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (CFStringRef)self, NULL, CFSTR(":/?#[]@!$ &'()*+,;=\"<>%{}|\\^~`"), kCFStringEncodingUTF8));    return encodedString;}- (NSString *)stringDecode {    NSString *result = [(NSString *)self stringByReplacingOccurrencesOfString:@"+" withString:@" "];    result = [result stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];    return result;}3）sizeFromFont- (CGSize)boundingRectWithSize:(CGSize)size                  withTextFont:(UIFont *)font {    if ([self isEqualToString:@""]) {        return CGSizeMake(0, 0);    }    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];    paragraphStyle.lineBreakMode = NSLineBreakByWordWrapping;    paragraphStyle.lineSpacing = 0;    NSDictionary *attributes = @{NSFontAttributeName:font, NSParagraphStyleAttributeName:paragraphStyle.copy};    return [self boundingRectWithSize:size options:NSStringDrawingUsesLineFragmentOrigin attributes:attributes context:nil].size;}4) 是否是邮箱格式- (BOOL)isEmail{    NSString *emailRegEx =      @"(?:[a-z0-9!#$%\\&'*+/=?\\^_`{|}~-]+(?:\\.[a-z0-9!#$%\\&'*+/=?\\^_`{|}"      @"~-]+)*|\"(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21\\x23-\\x5b\\x5d-\\"     @"x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])*\")@(?:(?:[a-z0-9](?:[a-"      @"z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\\[(?:(?:25[0-5"      @"]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-"      @"9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21"      @"-\\x5a\\x53-\\x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])+)\\])";      NSPredicate *regExPredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegEx];      return [regExPredicate evaluateWithObject:[self lowercaseString]];  }5) Base64- (NSString *)base64 {    // Create NSData object    NSData *nsdata = [self dataUsingEncoding:NSUTF8StringEncoding];    // Get NSString from NSData object in Base64    NSString *base64Encoded = [nsdata base64EncodedStringWithOptions:0];    // Print the Base64 encoded string    return base64Encoded;}- (NSString *)base64Decoded {    // NSData from the Base64 encoded str    NSData *nsdataFromBase64String = [[NSData alloc] initWithBase64EncodedString:self options:0];    // Decoded NSString from the NSData    NSString *base64Decoded = [[NSString alloc] initWithData:nsdataFromBase64String encoding:NSUTF8StringEncoding];    return base64Decoded;}