溫故知新，常用常新
//1、創建常量字符串。
NSString *astring = @"This is a String!";
//2、創建空字符串，給予賦值。
NSString *astring = [[NSString alloc] init]; astring = @"This is a String!"; [astring release]; NSLog(@"astring:%@",astring); // NSString *astring = [[NSString alloc] init]; NSLog(@"0x%.8x", astring); astring=@"This is a String!"; NSLog(@"0x%.8x", astring); [astring release]; 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); [astring release];
//4、用標準c創建字符串:initWithCString方法
char *Cstring = "This is a String!"; NSString *astring = [[NSString alloc] initWithCString:Cstring]; NSLog(@"astring:%@",astring); [astring release];
//5、創建格式化字符串:佔位符（由一個%加一個字符組成）
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、創建臨時字符串
NSString *astring; astring = [NSString stringWithCString:"This is a temporary string"]; NSLog(@"astring:%@",astring);
//7、從文件創建字符串
NSString *path = [[NSBundlemainBundle] pathForResource:@"astring.text"ofType:nil];
NSString *astring = [[NSString alloc] initWithContentsOfFile:path];
NSLog(@"astring:%@",astring);
[astring release];
//8、用字符串創建字符串，並寫入到文件
NSString *astring = [[NSString alloc] initWithString:@"This is a String!"]; NSLog(@"astring:%@",astring); NSString *path = @"astring.text"; [astring writeToFile: path atomically: YES]; [astring release];
//9、用C比較:strcmp函數
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返回的三種值)
// NSString *astring01 = @"This is a String!"; NSString *astring02 = @"This is a String!"; BOOL result = [astring01 compare:astring02] == NSOrderedSame; //NSOrderedSame判斷兩者內容是否相同 NSLog(@"result:%d",result); // NSString *astring01 = @"This is a String!"; NSString *astring02 = @"this is a String!"; BOOL result = [astring01 compare:astring02] == NSOrderedAscending; //NSOrderedAscending判斷兩對象值的大小(按字母順序進行比較，astring02大於astring01爲真) NSLog(@"result:%d",result); // NSString *astring01 = @"this is a String!"; NSString *astring02 = @"This is a String!"; BOOL result = [astring01 compare:astring02] == NSOrderedDescending; //NSOrderedDescending判斷兩對象值的大小(按字母順序進行比較，astring02小於astring01爲真) NSLog(@"result:%d",result);
//12、不考慮大小寫比較字符串
//1. NSString *astring01 = @"this is a String!"; NSString *astring02 = @"This is a String!"; BOOL result = [astring01 caseInsensitiveCompare:astring02] == NSOrderedSame; //NSOrderedDescending判斷兩對象值的大小(按字母順序進行比較，astring02小於astring01爲真) 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:不區分大小寫比較 NSLiteralSearch:進行完全比較，區分大小寫 NSNumericSearch:比較字符串的字符個數，而不是字符值。 NSLog(@"result:%d",result);
//13、輸出大寫或者小寫字符串
NSString *string1 = @"A String"; NSString *string2 = @"String"; NSLog(@"string1:%@",[string1 uppercaseString]);//大寫 NSLog(@"string2:%@",[string2 lowercaseString]);//小寫 NSLog(@"string2:%@",[string2 capitalizedString]);//首字母大小
//14、-rangeOfString: //查找字符串某處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: 從字符串的開頭一直截取到指定的位置，但不包括該位置的字符
NSString *string1 = @"This is a string"; NSString *string2 = [string1 substringToIndex:3]; NSLog(@"string2:%@",string2);
//16、-substringFromIndex: 以指定位置開始（包括指定位置的字符），幷包括之後的全部字符
NSString *string1 = @"This is a string"; NSString *string2 = [string1 substringFromIndex:3]; NSLog(@"string2:%@",string2);
//17、-substringWithRange: //按照所給出的位置，長度，任意地從字符串中截取子串
NSString *string1 = @"This is a string"; NSString *string2 = [string1 substringWithRange:NSMakeRange(0, 4)]; NSLog(@"string2:%@",string2);
//18、-stringWithCapacity: //按照固定長度生成空字符串
NSMutableString *String;
String = [NSMutableString stringWithCapacity:40];
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);
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"]; [String1 insertString:@"Hi! " atIndex:0]; NSLog(@"String1:%@",String1);
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"]; [String1 setString:@"Hello Word!"]; NSLog(@"String1:%@",String1);
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"]; [String1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"]; NSLog(@"String1:%@",String1);
NSString *String1 = @"NSStringInformation.txt"; [String1 hasPrefix:@"NSString"] = = 1 ? NSLog(@"YES") : NSLog(@"NO"); [String1 hasSuffix:@".txt"] = = 1 ? NSLog(@"YES") : NSLog(@"NO");
//24、擴展路徑
NSString *Path = @"~/NSData.txt"; NSString *absolutePath = [Path stringByExpandingTildeInPath]; NSLog(@"absolutePath:%@",absolutePath); NSLog(@"Path:%@",[absolutePath stringByAbbreviatingWithTildeInPath]);
//25、文件擴展名
NSString *Path = @"~/NSData.txt"; NSLog(@"Extension:%@",[Path pathExtension]);
