NSString的各种修改方法

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一、NSString

创建字符串。

NSString *astring = @"This is a String!";

创建空字符串，给予赋值。

NSString *astring = [[NSString alloc] init];

astring = @"This is a String!";

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

string release];

使用变量初始化

NSString *name = @"Ivan!";

NSString *astring = [[NSString stringWithFormat:@”My name is %@!”,name]];

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

判断是否包含某字符串

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");

是否包含其它字符

NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];

Boolean contains = [astring rangeOfString:@”This”].length>0;

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];

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];

比较两个字符串

isEqualToString方法

NSString *astring01 = @"This is a String!";

NSString *astring02 = @"This is a String!";

BOOL result = [astring01 isEqualToString:astring02];

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

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);

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);

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

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];

替换字符串

NSString *astring01 = @"hello 中国";

NSString * new = [astring01 stringByReplacingOccurrencesOfString:@”中国” withString:@"北京"];

NSLog(new);

分割字符串成数组

NSString *s = @"a b d e f";

NSArray *arr = [s componentsSeparatedByString:@" "];

NSLog(@"count = %d",[arr count]);

字符串数组拼接成字符串

NSArray *pathArray = [NSArray arrayWithObjects:@"here",

@"be",@"dragons", nil];

NSLog(@"%@",[pathArray componentsJoinedByString:@""]);

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);

-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);

二、NSMutableString

给字符串分配容量

//stringWithCapacity:

NSMutableString *String;

String = [NSMutableString stringWithCapacity:40];

在已有字符串后面添加字符

//appendString: and appendFormat: