Objective-C中使用NSString類操作字符串的方法小結(jié)

更新時(shí)間：2016年01月18日 09:21:38 作者：芳草小腳印

這篇文章主要介紹了Objective-C中使用NSString類操作字符串的方法小結(jié),文中講到了字符串的分割和拼接等一些常見的用法,需要的朋友可以參考下

一、字符串切割
1、帶節(jié)點(diǎn)的字符串，如@"<p>討厭的節(jié)點(diǎn)<br/></p>"我們只想要中間的中文

處理方法：

NSString *string1 = @"<p>討厭的節(jié)點(diǎn)<br/></p>";

/*此處將不想要的字符全部放進(jìn)characterSet1中，不需另外加逗號或空格之類的，除非字符串中有你想要去除的空格，此處< p /等都是單獨(dú)存在，不作為整個(gè)字符*/

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

// 將string1按characterSet1中的元素分割成數(shù)組

NSArray *array1 = [string1 componentsSeparatedByCharactersInSet:characterSet1];

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

for(NSString *string1 in array1)

{

    if ([string1 length]>0) {

        // 此處string即為中文字符串

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

    }

}

打印結(jié)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 = 討厭的節(jié)點(diǎn)

2、帶空格的字符串，如

@"hello world"去掉空格

復(fù)制代碼代碼如下:

NSString *string2 = @"hello world";

/*處理空格*/

NSCharacterSet *characterSet2 = [NSCharacterSet whitespaceCharacterSet];

// 將string1按characterSet1中的元素分割成數(shù)組

NSArray *array2 = [string2 componentsSeparatedByCharactersInSet:characterSet2];

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

// 用來存放處理后的字符串

NSMutableString *newString1 = [NSMutableString string];

for(NSString *string in array1)

{

    [newString1 appendString:string];

}

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

打印結(jié)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：處理字母等其他元素只需將NSCharacterSet的值改變即可。

復(fù)制代碼代碼如下:

+ (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、用字符將NSArray中的元素拼接起來

復(fù)制代碼代碼如下:

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

//如要用,:等字符串拼接，只需將下面的@" "空格換成@","或@":"即可

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

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

打印結(jié)果：

hello world

三、截取子串：

這里以獲取時(shí)間為例，利用NSDate獲取到當(dāng)前時(shí)間時(shí)，有時(shí)候只需要日期或者只需要時(shí)間

1、從字符串開頭截取到指定的位置，如

復(fù)制代碼代碼如下:

//獲取到當(dāng)前日期時(shí)間    

NSDate *date = [NSDate date];

//定義日期格式,此處不重點(diǎn)討論NSDate，故不詳細(xì)說明，在后面會詳細(xì)討論       

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

//設(shè)置日期格式        

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

//將日期轉(zhuǎn)換成NSString類型      

NSString *string = [dateformatter stringFromDate:date];

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

//截取日期substringToIndex 

NSString *currentDate = [string substringToIndex:10];

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

打印結(jié)果：

current = 2016-01-1711:12


currentDate = 2016-01-17

2、抽取中間子串-substringWithRange

復(fù)制代碼代碼如下:

//截取月日

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

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

打印結(jié)果：

currentMonthAndDate = 06-27

3、從某一位置開始截取- substringFromIndex

復(fù)制代碼代碼如下:

//截取時(shí)間substringFromIndex

NSString *currentTime = [string substringFromIndex:11];

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

打印結(jié)果：

currentTime = 11:25

四、比較字符串

復(fù)制代碼代碼如下:

NSString *first = @"string";

NSString *second = @"String";

1、判斷兩個(gè)字符串是否相同-isEqualToString方法

復(fù)制代碼代碼如下:

BOOL isEqual = [first isEqualToString:second];

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

打印結(jié)果：

first is Equal to second:0

2、compare方法比較字符串三個(gè)值

復(fù)制代碼代碼如下:

NSOrderedSame//是否相同
NSOrderedAscending//升序，按字母順序比較，大于為真
NSOrderedDescending//降序，按字母順序比較，小于為真

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

打印結(jié)果：

result:0

復(fù)制代碼代碼如下:

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

打印結(jié)果：

result:0

復(fù)制代碼代碼如下:

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

打印結(jié)果：

result:1

3、不考慮大小寫比較字符串

復(fù)制代碼代碼如下:

BOOL result = [first compare:second

                     options:NSCaseInsensitiveSearch | NSNumericSearch] == NSOrderedSame;

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

打印結(jié)果：

result:1

五、改變字符串大小寫

復(fù)制代碼代碼如下:

NSString *aString = @"A String"; 

NSString *string = @"String"; 

//大寫

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

//小寫

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

//首字母大小寫

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

打印結(jié)果：

aString:A STRING

string:string

string:String

六、在字符串中搜索子串

復(fù)制代碼代碼如下:

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];

打印結(jié)果：