ios-NSString总结

1.常用功能使用

1）初始化

2）截取

3）分解

4）查找

5）替换

6）路径相关

7）字符串是否为空

8）字符串比较

9）字符串比大小

2.常用扩展功能(类别扩展)

1）md5

2）urlEncode

3）sizeFromFont

4) 是否是邮箱格式

5) Base64

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
        [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;
}