NSString *str1 = @"BeiJing";
NSString *str2 = @"beijing";
//全部转为大写
NSLog(@"%@",[str1 uppercaseString]);
//全部转为小写
NSLog(@"%@",[str1 lowercaseString]);
//首字母大写
NSLog(@"%@",[str1 capitalizedString]);
//比较两个字符串内容是否相同
BOOL b =[str1 isEqualToString:str2];
//5.两个字符串内容比较
//NSOrderedAscending 右边 > 左边
//NSOrderedSame 内容相同
//NSOrderedDescending 左边 > 右边
NSComparisonResult result = [str1 compare:str2];
if (result == NSOrderedAscending) {
NSLog(@"右边 > 左边");
}else if(result == NSOrderedSame){
NSLog(@"内容相同");
}else if (result == NSOrderedDescending){
NSLog(@"左边 > 右边");
}
//忽略大小写进行比较，返回值与compare一样
result = [str1 caseInsensitiveCompare:str2];
if (result == NSOrderedAscending) {
NSLog(@"右边 > 左边");
}else if(result == NSOrderedSame){
NSLog(@"内容相同");
}else if (result == NSOrderedDescending){
NSLog(@"左边 > 右边");
}
//判断字符串是否以指定字符串开头
[str1 hasPrefix:@"aaa"];
//判断字符串是否以指定字符串结尾
[str1 hasSuffix:@"aaa"];
//判断字符串是否包含指定字符串，返回位置和长度
NSRange range = [@"123456" rangeOfString:@"456"];
NSLog(@"%@", NSStringFromRange(range));
//反向搜索
range = [@"123456456qweasasd456" rangeOfString:@"456" options:NSBackwardsSearch];
NSLog(@"%@",NSStringFromRange(range));
//指定范围进行搜索
range = NSMakeRange(0, 9);
range = [@"123456456qweasasd456" rangeOfString:@"456" options:NSBackwardsSearch range:range];
NSLog(@"%@",NSStringFromRange(range));
//字符串的截取
NSString *str = @"123456789";
NSLog(@"%@",[str substringFromIndex:3]);
NSLog(@"%@",[str substringToIndex:6]);
NSLog(@"%@",[str substringWithRange:NSMakeRange(3, 3)]);
//用指定字符串分割字符串，返回一个数组
NSArray *array = [@"1,2,3,4,5,6" componentsSeparatedByString:@","];
NSLog(@"%@",array);
//将数组中的字符串组合成一个文件路径
NSMutableArray *components = [NSMutableArray array];
[components addObject:@"Users"];
[components addObject:@"CentralPerk"];
[components addObject:@"Desktop"];
NSString *path = [NSString pathWithComponents:components];
NSLog(@"%@",path); //Users/CentralPerk/Desktop
//将一个路径分割成一个数组
NSArray *array1 = [path pathComponents];
NSLog(@"%@",array1);
//判断是否为绝对路径(依据：是否以'/'开始)
path = @"/Users/CentralPerk/Desktop";
NSLog(@"%i",[path isAbsolutePath]);
//获取最后一个目录
NSLog(@"%@",[path lastPathComponent]);
//删除最后一个目录
NSLog(@"%@",[path stringByDeletingLastPathComponent]);
//拼接一个目录
NSLog(@"%@",[path stringByAppendingPathComponent:@"aaa"]); ///Users/CentralPerk/Desktop/aaa
NSLog(@"%@",[path stringByAppendingString:@"aaa"]); ///Users/CentralPerk/Desktopaaa
NSLog(@"%@",[path stringByAppendingFormat:@"%@%@",@"b",@"c"]); ///Users/CentralPerk/Desktopbc
//拓展名出来
//获取拓展名,不带.
NSString *str3 = @"Users/CentralPerk/Desktop/test.txt";
NSLog(@"%@",[str3 pathExtension]);
//添加拓展名,不需要带.
NSLog(@"%@",[str3 stringByAppendingPathExtension:@"mp3"]);
//删除拓展名,带.一块删除
NSLog(@"%@",[str3 stringByDeletingPathExtension]);
//字符串转为 int double float
NSString *str4 = @"123";
NSLog(@"%i",[str4 intValue]);
NSLog(@"%zi",[str4 length]);
//取出指定位置的字符
unichar c = [str4 characterAtIndex:2];
NSLog(@"%c",c);
//转为C语言的字符串
const char *s = [str4 UTF8String];
NSLog(@"%s",s);
//去掉两端的空格
[str stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
//去掉多余的空格
NSString *str = @" this is a test . ";
NSCharacterSet *whitespaces = [NSCharacterSet whitespaceCharacterSet];
NSPredicate *noEmptyStrings = [NSPredicate predicateWithFormat:@"SELF != ''"];
NSArray *parts = [str componentsSeparatedByCharactersInSet:whitespaces];
NSArray *filteredArray = [parts filteredArrayUsingPredicate:noEmptyStrings];
str = [filteredArray componentsJoinedByString:@" "];
//去掉所有空格
[str stringByReplacingOccurrencesOfString:@" " withString:@""]
//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!";
NSLog(@"astring:%@",astring);
//
NSString *astring = [[NSString alloc] init];
NSLog(@"0x%.8x", astring);
astring=@"This is a String!";
NSLog(@"0x%.8x", astring);
NSLog(@"astring:%@",astring);
//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);
//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);
//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);
//6、创建临时字符串
NSString *astring;
astring = [NSString stringWithCString:"This is a temporary string"];
NSLog(@"astring:%@",astring);
//7、从文件创建字符串
NSString *path = [[NSBundlemainBundle] pathForResource:@"astring.text"ofType:nil];
NSString *astring = [[NSString alloc] initWithContentsOfFile:path];
NSLog(@"astring:%@",astring);
//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!"];
NSLog(@"astring:%@",astring);
NSString *path = @"astring.text";//注：此路径path只只是示意，真实路径并非如此
[astring writeToFile: path atomically: YES];
//9、用C比较:strcmp函数
char string1[] = "string!";
char string2[] = "string!";
if(strcmp(string1, string2) == 0){
NSLog(@"1");
}
//10、isEqualToString方法
NSString *astring01 = @"This is a String!";
NSString *astring02 = @"This is a String!";
BOOL result = [astring01 isEqualToString:astring02];
NSLog(@"result:%d",result);
//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
NSLog(@"result:%d",result);
//
NSString *astring01 = @"This is a String!";
NSString *astring02 = @"this is a String!";
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)
NSLog(@"result:%d",result);
//
NSString *astring01 = @"this is a String!";
NSString *astring02 = @"This is a String!";
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)
NSLog(@"result:%d",result);
//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)
NSLog(@"result:%d",result);
//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。
NSLog(@"result:%d",result);
//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);
//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: 替换字符串
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]);
//26、剪切 字符串 ，按照range的要求，从第几个开始 ， 剪切的长度为几
NSMutableString *a = [[NSMutableString alloc] initWithString:@"123456798"];
NSLog(@" \n a: %@ \n",a);
[a deleteCharactersInRange:NSMakeRange(1, 2)];
NSLog(@" \n a: %@ \n",a);
// 2011-07-05 20:59:34.169 Q[9069:207] a: 123456798
// 2011-07-05 20:59:34.171 Q[9069:207] a: 1456798