iOS开发之一些字符串常用的代码

http://www.cnblogs.com/zhuqil/archive/2011/08/03/2126524

1、判断字符串是否相等使用isEqualToString：

NSString *astring01 = @"This is a String!";
NSString *astring02 = @"This is a String!";
BOOL result = [astring01 isEqualToString:astring02];
NSLog(@"result:%d",result);

2、判断字符不相等：

NSString *astring01 = @"This is a String!";
NSString *astring02 = @"This is a String!";
if ([astring01 compare: astring02]!=NSOrderedSame )
{
NSLog(@"not equal");
}

3、判断字符串是否为空。

NSString *urlString = [urlInput stringValue];

if (!urlString) {

NSLog( @”NO INPUT.” );

} else {

if ([urlString length] == 0 ) {

NSLog( @”NO INPUT.” );

} else {

}

}
}

http://blog.csdn.net/tt5267621/article/details/7670515

//1、创建常量字符串。

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

//2、创建空字符串，给予赋值。

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

astring = @"This is a String!";

[astring release];

//

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

astring=@"This is a String!";

[astring release];

//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];

//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];

[astring release];

//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]];

[astring release];

//6、创建临时字符串

NSString *astring;

astring = [NSString stringWithCString:"This is a temporary string"];

//7、从文件创建字符串

NSString *path = [[NSBundlemainBundle] pathForResource:@"astring.text"ofType:nil];

NSString *astring = [[NSString alloc] initWithContentsOfFile:path];

[astring release];

//8、用字符串创建字符串，并写入到文件

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

NSString *path = @"astring.text";

[astring writeToFile: path atomically: YES];

[astring release];

注：此路径path只是示意，真实路径并非如此

//9、用C比较:strcmp函数

char string1[] = "string!";

char string2[] = "string!";

if(strcmp(string1, string2) == 0){}

//10、isEqualToString方法

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

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

BOOL result = [astring01 isEqualToString:astring02];

//11、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;    //NSOrderedSame判断两者内容是否相同

//标准写法
if (str1!=nil && [str1 compare:@"some text"] == NSOrderedSame) {}

//

BOOL result = [astring01 compare:astring02] == NSOrderedAscending;    //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)

BOOL result = [astring01 compare:astring02] == NSOrderedDescending;    //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)

//12、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;    //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)

//2.
NSString *astring01 = @"this is a String!";

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

BOOL result = [astring01 compare:astring02

options:NSCaseInsensitiveSearch | NSNumericSearch] == NSOrderedSame;    //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。

//13、输出大写或者小写字符串

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

//14、-rangeOfString: //查找字符串某处是否包含其它字符串

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];

//15、-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);

//16、-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);

//17、-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);

//18、-stringWithCapacity: //按照固定长度生成空字符串

NSMutableString *String;

String = [NSMutableString stringWithCapacity:40];

//19、-appendString: and -appendFormat: //把一个字符串接在另一个字符串的末尾

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);

//20、-insertString: atIndex: //在指定位置插入字符串

NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];

[String1 insertString:@"Hi! " atIndex:0];

NSLog(@"String1:%@",String1);

//21、-setString:

NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];

[String1 setString:@"Hello Word!"];

NSLog(@"String1:%@",String1);

//22、-replaceCharactersInRange: withString: //用指定字符串替换字符串中某指定位置、长度的字符串

NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];

[String1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"];

NSLog(@"String1:%@",String1);

//23、-hasPrefix: //检查字符串是否以另一个字符串开头

NSString *String1 = @"NSStringInformation.txt";

[String1 hasPrefix:@"NSString"] = = 1 ?  NSLog(@"YES") : NSLog(@"NO");

[String1 hasSuffix:@".txt"] = = 1 ?  NSLog(@"YES") : NSLog(@"NO");

//24、扩展路径

NSString *Path = @"~/NSData.txt";

NSString *absolutePath = [Path stringByExpandingTildeInPath];

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

NSLog(@"Path:%@",[absolutePath stringByAbbreviatingWithTildeInPath]);

//25、文件扩展名

NSString *Path = @"~/NSData.txt";

NSLog(@"Extension:%@",[Path pathExtension]);