Objective-C中使用NSString类操作字符串的方法小结

一、字符串切割
1、带节点的字符串，如@"<p>讨厌的节点<br/></p>"我们只想要中间的中文

处理方法：

NSString *string1 = @"<p>讨厌的节点<br/></p>";

 

/*此处将不想要的字符全部放进characterSet1中，不需另外加逗号或空格之类的，除非字符串中有你想要去除的空格，此处< p /等都是单独存在，不作为整个字符*/

 

NSCharacterSet *characterSet1 = [NSCharacterSet characterSetWithCharactersInString:@"<p/brh>"];

 

// 将string1按characterSet1中的元素分割成数组

 

NSArray *array1 = [string1 componentsSeparatedByCharactersInSet:characterSet1];

 

NSLog(@"array = %@",array1);

 

for(NSString *string1 in array1)

{

    if ([string1 length]>0) {

         

        // 此处string即为中文字符串

 

        NSLog(@"string = %@",string1);

    }

}

打印结果：

2016-01-17 10:55:34.017 string[17634:303] 
array = (
 "",
 "",
 "",
 "\U8ba8\U538c\U7684\U8282\U70b9",
 "",
 "",
 "",
 "",
 "",
 "",
 "",
 "",
 ""
)
2016-01-17 10:55:34.049 string[17634:303] 
string = 讨厌的节点

2、带空格的字符串，如

@"hello world"去掉空格

NSString *string2 = @"hello world";

 

/*处理空格*/

 

NSCharacterSet *characterSet2 = [NSCharacterSet whitespaceCharacterSet];

 

// 将string1按characterSet1中的元素分割成数组

NSArray *array2 = [string2 componentsSeparatedByCharactersInSet:characterSet2];

 

NSLog(@"\narray = %@",array2);

 

// 用来存放处理后的字符串

NSMutableString *newString1 = [NSMutableString string];

 

for(NSString *string in array1)

{

    [newString1 appendString:string];

}

NSLog(@"newString = %@", newString1);

打印结果：

2016-01-17 11:02:49.656 string[17889:303] 
array = (
 hello,
 world
)
2016-01-17 11:02:49.657 string[17889:303] newString = helloworld

PS：处理字母等其他元素只需将NSCharacterSet的值改变即可。

+ (id)controlCharacterSet;

 

+ (id)whitespaceCharacterSet;

 

+ (id)whitespaceAndNewlineCharacterSet;

 

+ (id)decimalDigitCharacterSet;

 

+ (id)letterCharacterSet;

 

+ (id)lowercaseLetterCharacterSet;

 

+ (id)uppercaseLetterCharacterSet;

 

+ (id)nonBaseCharacterSet;

 

+ (id)alphanumericCharacterSet;

 

+ (id)decomposableCharacterSet;

 

+ (id)illegalCharacterSet;

 

+ (id)punctuationCharacterSet;

 

+ (id)capitalizedLetterCharacterSet;

 

+ (id)symbolCharacterSet;

 

+ (id)newlineCharacterSet NS_AVAILABLE(10_5, 2_0);

 

+ (id)characterSetWithRange:(NSRange)aRange;

 

+ (id)characterSetWithCharactersInString:(NSString *)aString;

 

+ (id)characterSetWithBitmapRepresentation:(NSData *)data;

 

+ (id)characterSetWithContentsOfFile:(NSString *)fName;

二、用字符将NSArray中的元素拼接起来

NSArray *array = [NSArray arrayWithObjects:@"hello",@"world",nil];

 

//如要用,:等字符串拼接，只需将下面的@" "空格换成@","或@":"即可

NSString *string = [array componentsJoinedByString:@" "];

 

NSLog(@"string = %@",string);

打印结果：

hello world

三、截取子串：

这里以获取时间为例，利用NSDate获取到当前时间时，有时候只需要日期或者只需要时间

1、从字符串开头截取到指定的位置，如

//获取到当前日期时间    

NSDate *date = [NSDate date];

         

//定义日期格式,此处不重点讨论NSDate，故不详细说明，在后面会详细讨论       

NSDateFormatter *dateformatter = [[NSDateFormatter alloc] init];

         

//设置日期格式        

[dateformatter setDateFormat:@"YYYY-MM-dd HH:mm"];

         

//将日期转换成NSString类型      

NSString *string = [dateformatter stringFromDate:date];

NSLog(@"\ncurrent = %@",string);

                

//截取日期substringToIndex 

NSString *currentDate = [string substringToIndex:10];

                 

NSLog(@"\ncurrentDate = %@",currentDate);

打印结果：

current = 2016-01-1711:12


currentDate = 2016-01-17

2、抽取中间子串-substringWithRange

//截取月日

NSString *currentMonthAndDate = [string substringWithRange:[NSMakeRange(5, 5)]];

         

NSLog(@"currentMonthAndDate = %@",currentMonthAndDate);

打印结果：

currentMonthAndDate = 06-27

3、从某一位置开始截取- substringFromIndex

//截取时间substringFromIndex

NSString *currentTime = [string substringFromIndex:11];

         

NSLog(@"\ncurrentTime = %@",currentTime);\

打印结果：

currentTime = 11:25

四、比较字符串

NSString *first = @"string";

NSString *second = @"String";

1、判断两个字符串是否相同-isEqualToString方法

BOOL isEqual = [first isEqualToString:second];

 

NSLog(@"first is Equal to second:%@",isEqual);

打印结果：

first is Equal to second:0

2、compare方法比较字符串三个值

NSOrderedSame//是否相同

NSOrderedAscending//升序，按字母顺序比较，大于为真

NSOrderedDescending//降序，按字母顺序比较，小于为真

BOOL result = [first compare:sencond] == NSOrderedSame;    

NSLog(@"result:%d",result);

打印结果：

result:0 

BOOL result = [first compare:second] == NSOrderedAscending;    

NSLog(@"result:%d",result);

打印结果：

result:0

BOOL result = [first compare:second] == NSOrderedDecending; NSLog(@"result:%d",result);

打印结果：

result:1

3、不考虑大小写比较字符串

BOOL result = [first compare:second

                     options:NSCaseInsensitiveSearch | NSNumericSearch] == NSOrderedSame;

NSLog(@"result:%d",result);

打印结果：

result:1

五、改变字符串大小写

NSString *aString = @"A String"; 

NSString *string = @"String"; 

//大写

NSLog(@"aString:%@",[aString uppercaseString]);

//小写

NSLog(@"string:%@",[string lowercaseString]);

//首字母大小写

NSLog(@"string:%@",[string capitalizedString]);

打印结果：

aString:A STRING

string:string

string:String

六、在字符串中搜索子串

NSString *string1 = @"This is a string";

NSString *string2 = @"string";

NSRange range = [string1 rangeOfString:string2];

NSUInteger location = range.location;

NSUInteger leight = range.length;

NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"Location:%li,Leight:%li",location,leight]];

NSLog(@"astring:%@",astring);

[astring release];

打印结果：

astring:Location:10,Leight:6