obj-c 常用字符串处理方法
obj-c 常用字符串处理方法
1、创建常量字符串。
NSString *astring = “This is a String!”;
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2、创建空字符串，给予赋值。
NSString *astring = [[NSString alloc] init];
astring = “This is a String!”;
NSLog( “astring:% “,astring);
[astring release];
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3、在以上方法中，提升速度:initWithString方法
NSString *astring = [[NSString alloc] initWithString: “This is a
String!”];
NSLog( “astring:% “,astring);
[astring release];
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4、用标准c创建字符串:initWithCString方法
char *Cstring = “This is a String!”;
NSString *astring = [[NSString alloc]
initWithCString:Cstring];
NSLog( “astring:% “,astring);
[astring release];
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5、创建格式化字符串:占位符（由一个%加一个字符组成）
int i = 1;
int j = 2;
NSString *astring = [[NSString alloc]
initWithString:[NSString stringWithFormat: “%d.This is %i
string!”,i,j]];
NSLog( “astring:% “,astring);
[astring release];
6、创建临时字符串
NSString *astring;
astring = [NSString stringWithCString:”This is a temporary
string”];
NSLog( “astring:% “,astring);
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7、判断字符串为空
NSString *urlString = [urlInput stringValue];
if (!urlString) {
NSLog( ”NO INPUT.” );
}
if ([urlString length] == 0 ) {
NSLog( ”NO INPUT.” );
}
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9、是否以”test”开头;是否以”.move”结尾;
NSString *fileName = ”test.move”;
if
([fileName hasPrefix: “test”]) {
NSLog( ”has
Test String !”);
}else{
NSLog( ”don’t
have Test”);
}
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[fileName
hasSuffix: “.move”]?NSLog( ”Yes it got a .Mov in its end”):NSLog( ”no
it has no .mov string”);
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10、比较两个字符串:
strcmp函数
char string1[] = “string!”;
char string2[] = “string!”;
if(strcmp(string1, string2) = = 0)
{
NSLog( “1”);
}
isEqualToString方法
NSString *astring01 = “This is a String!”;
NSString *astring02 = “This is a String!”;
BOOL result = [astring01 isEqualToString:astring02];
NSLog( “result:%d”,result);
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compare方法(comparer返回的三种值)
NSString *astring01 = “This is a String!”;
NSString *astring02 = “This is a String!”;
BOOL result = [astring01 compare:astring02] = =
NSOrderedSame;
NSLog( “result:%d”,result);
NSOrderedSame 判断两者内容是否相同
NSString *astring01 = “This is a String!”;
NSString *astring02 = “this is a String!”;
BOOL result = [astring01 compare:astring02] = =
NSOrderedAscending;
NSLog( “result:%d”,result);
NSOrderedAscending 判断两对象值的大小(按字母顺序进行比较，astring02大于astring01为真)
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NSString *astring01 = “this is a String!”;
NSString *astring02 = “This is a String!”;
BOOL result = [astring01 compare:astring02] = =
NSOrderedDescending;
NSLog( “result:%d”,result);
NSOrderedDescending 判断两对象值的大小(按字母顺序进行比较，astring02小于astring01为真)
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不考虑大 小写比较字符串1
NSString *astring01 = “this is a String!”;
NSString *astring02 = “This is a String!”;
BOOL result = [astring01 caseInsensitiveCompare:astring02]
= = NSOrderedSame;
NSLog( “result:%d”,result);
NSOrderedDescending判断两对象值的大小(按字母顺序进行比较，astring02小于astring01为真)
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不考虑大小写比较字符串2
NSString *astring01 = “this is a String!”;
NSString *astring02 = “This is a String!”;
BOOL result = [astring01 compare:astring02
options:NSCaseInsensitiveSearch |
NSNumericSearch] = = NSOrderedSame;
NSLog( “result:%d”,result);
NSCaseInsensitiveSearch:不区分大小写比较 NSLiteralSearch:进行完全比较，区分大小写NSNumericSearch:比较字符串的字符个数，而不是字符值。
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11、声明一个可变字符;长度是40个字符;
NSMutableString
*myMutableString;
myMutableString
= [NSMutableString stringWithCapacity:40];
NSString
*myName = ”Leo”;
[myMutableString
appendString: “Hello ,there”];
[myMutableString
appendFormat: “ i am % “,myName];
NSLog( ”this
is NSMutableString: % ”,myMutableString);
//this
is NSMutableString: Hello ,there i am Leo;
12、修改可变字符;先声明一个可变字符 myFriend;长度30;
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NSMutableString
*myGirlFriend;
myGirlFriend =
[NSMutableString stringWithCapacity:30];
//然后给字符加入一些内容;
[myGirlFriend
appendString: “Here are my GF:Carol Sophia Ashley Helen and Yoyo”];
NSLog( ”% ”,myGirlFriend);
//声名一个变动范围(NSRange);
NSRange
joneRange;
joneRange =
[myGirlFriend rangeOfString: “Helen “];
//下面:就是从myFriend字符中配对,如果有相等的内容就删除了;
[myGirlFriend
deleteCharactersInRange:joneRange];
NSLog( ”% ”,myGirlFriend);
13、在一个字符串后面附加一个新的字符串
NSString *a = “a”;
NSString *b = [a stringByAppendingString: “b”];//b变量的值为“ab”
14、字符串转换整数值
NSString *age = “36”;
if([age intValue]>35){
}
15、从文件读取字符串:initWithContentsOfFile方法
NSString *path = “astring.text”;
NSString *astring = [[NSString alloc]
initWithContentsOfFile:path];
NSLog( “astring:% “,astring);
[astring release];
16、写字符串到文件:writeToFile方法
NSString *astring = [[NSString alloc]
initWithString: “This is a String!”];
NSLog( “astring:% “,astring);
NSString *path = “astring.text”;
[astring writeToFile: path atomically: YES];
[astring release];
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17、改变字符串的大小写
NSString *string1 = “A String”;
NSString *string2 = “String”;
NSLog( “string1:% “,[string1 uppercaseString]);//大写
NSLog( “string2:% “,[string2 lowercaseString]);//小写
NSLog( “string2:% “,[string2 capitalizedString]);//首字母大小
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18、在串中搜索子串
NSString *string1 = “This is a string”;
NSString *string2 = “string”;
NSRange range = [string1 rangeOfString:string2];
int location = range.location;
int leight = range.length;
NSString *astring = [[NSString alloc]
initWithString:[NSString
stringWithFormat: “Location:%i,Leight:%i”,location,leight]];
NSLog( “astring:% “,astring);
[astring release];
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19、抽取子串
//-substringToIndex: 从字符串的开头一直截取到指定的位置，但不包括该位置的字符
NSString *string1 = “This is a string”;
NSString *string2 = [string1 substringToIndex:3];
NSLog( “string2:% “,string2);
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//-substringFromIndex: 以指定位置开始（包括指定位置的字符），并包括之后的全部字符
NSString *string1 = “This is a string”;
NSString *string2 = [string1 substringFromIndex:3];
NSLog( “string2:% “,string2);
//-substringWithRange: //按照所给出的位置，长度，任意地从字符串中截取子串
NSString *string1 = “This is a string”;
NSString *string2 = [string1
substringWithRange:NSMakeRange(0, 4)];
NSLog( “string2:% “,string2);
20、扩展路径
NSString *Path = “~/NSData.txt”;
NSString *absolutePath = [Path
stringByExpandingTildeInPath];
NSLog( “absolutePath:% “,absolutePath);
NSLog( “Path:% “,[absolutePath
stringByAbbreviatingWithTildeInPath]);
21、文件扩展名
NSString *Path = “~/NSData.txt”;
NSLog( “Extension:% “,[Path pathExtension]);
22、在已有字符串后面添加字符
NSMutableString *String1 = [[NSMutableString alloc]
initWithString: “This is a NSMutableString”];
//[String1 appendString: “, I will be adding some
character”];
[String1 appendFormat:[NSString stringWithFormat: “, I will
be adding some character”]];
NSLog( “String1:% “,String1);
23、在已有字符串中按照所给出范围和长度删除字符
NSMutableString *String1 = [[NSMutableString alloc]
initWithString: “This is a NSMutableString”];
[String1 deleteCharactersInRange:NSMakeRange(0, 5)];
NSLog( “String1:% “,String1);
24、在已有字符串后面在所指定的位置中插入给出的字符串
//-insertString: atIndex:
NSMutableString *String1 = [[NSMutableString alloc]
initWithString: “This is a NSMutableString”];
[String1 insertString: “Hi! “ atIndex:0];
NSLog( “String1:% “,String1);
25、将已有的空符串换成其它的字符串
//-setString:
NSMutableString *String1 = [[NSMutableString alloc]
initWithString: “This is a NSMutableString”];
[String1 setString: “Hello Word!”];
NSLog( “String1:% “,String1);
26、按照所给出的范围，和字符串替换的原有的字符
//-setString:
NSMutableString *String1 = [[NSMutableString alloc]
initWithString: “This is a NSMutableString”];
[String1 replaceCharactersInRange:NSMakeRange(0, 4)
withString: “That”];
NSLog( “String1:% “,String1);
27、判断字符串内是否还包含别的字符串(前缀，后缀)
//01：检查字符串是否以另一个字符串开头-
(BOOL) hasPrefix: (NSString *) aString;
NSString *String1 = “NSStringInformation.txt”;
[String1 hasPrefix: “NSString”] = = 1 ? NSLog( “YES”) :
NSLog( “NO”);
[String1 hasSuffix: “.txt”] = = 1 ? NSLog( “YES”) :
NSLog( “NO”);
//02：查找字符串某处是否包含其它字符串 -
(NSRange) rangeOfString: (NSString *) aString，这一点前面在串中搜索子串用到过;
