-----从文件读取字符串-----
NSString *path = @"astring.text";
NSString *astring = [[NSString alloc] initWithContentsOfFile:path];
NSLog(@"astring:%@",astring);
[astring release];
-----写字符串到文件----
NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];
NSLog(@"astring:%@",astring);
NSString *path = @"astring.text";
[astring writeToFile: path atomically: YES];
[astring release];
-----比较两个字符串-----
//1、用C比较:strcmp函数
char string1[] = "string!";
char string2[] = "string!";
if(strcmp(string1, string2) = = 0)
{
NSLog(@"1");
}
//2、isEqualToString方法
NSString *astring01 = @"This is a String!";
NSString *astring02 = @"This is a String!";
BOOL result = [astring01 isEqualToString:astring02];
NSLog(@"result:%d",result);
//3、compare方法(comparer返回的三种值:NSOrderedSame,NSOrderedAscending,NSOrderedDescending)
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;
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)
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)
//4、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)
//5、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。
-----改变字符串的大小写-----
NSString *string1 = @"A String";
NSString *string2 = @"String";
NSLog(@"string1:%@",[string1 uppercaseString]);//uppercaseString返回转换为大写的字符串
NSLog(@"string2:%@",[string2 lowercaseString]);//lowercaseString返回转换为小写的字符串
NSLog(@"string2:%@",[string2 capitalizedString]);//capitalizedString返回每个单词首字母大写的字符串
-----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];
-----抽取子串 -----
//1、-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);
//2、-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);
//3、-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);
//5、枚举
NSEnumerator *filenum;
filenum = [files objectEnumerator];
while (filename = [filenum nextObject]) {
NSLog(@"filename:%@",filename);
}
-----切分数组-----
//1、从字符串分割到数组- componentsSeparatedByString:
NSString *string = [[NSString alloc] initWithString:@"One,Two,Three,Four"];
NSLog(@"string:%@",string);
NSArray *array = [string componentsSeparatedByString:@","];
NSLog(@"array:%@",array);
[string release];
//2、从数组合并元素到字符串- componentsJoinedByString:
NSArray *array = [[NSArray alloc] initWithObjects:@"One",@"Two",@"Three",@"Four",nil];
NSString *string = [array componentsJoinedByString:@","];
NSLog(@"string:%@",string);
-----从目录搜索扩展名为jpg的文件-----
//NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *home;
home = @"../Users/";
NSDirectoryEnumerator *direnum;
direnum = [fileManager enumeratorAtPath: home];
NSMutableArray *files = [[NSMutableArray alloc] init];
//枚举
NSString *filename;
while (filename = [direnum nextObject]) {
if([[filename pathExtension] hasSuffix:@"jpg"]){
[files addObject:filename];
}
}
//扩展路径
NSString *Path = @"~/NSData.txt";
NSString *absolutePath = [Path stringByExpandingTildeInPath];
NSLog(@"absolutePath:%@",absolutePath);
NSLog(@"Path:%@",[absolutePath stringByAbbreviatingWithTildeInPath]);
//文件扩展名
NSString *Path = @"~/NSData.txt";
NSLog(@"Extension:%@",[Path pathExtension]);
-----查找与替换-----
- (NSString *)stringByReplacingCharactersInRange:(NSRange)range withString:(NSString *)replacement
-----在已有字符串后面添加字符-----
//appendString: and appendFormat:
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);
----- 在已有字符串中按照所给出范围删除字符----
//deleteCharactersInRange:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 deleteCharactersInRange:NSMakeRange(0, 5)]; // 删除指定范围(location=0,length=5)的字符串
NSLog(@"String1:%@",String1);
----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);
[String1 insertString:@"and StringEnd", atIndex:[String1 length]]; // 在可变字符串的最后插入
----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);
----查找-----
NSRange subRange = [String1 rangeOfString:@"is a"]; // 如果没查找到,则 (subRange.location == NSNotFound)为真。
----按照所给出的范围替换的原有的字符-----
//-setString:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"]; // 用于NSMutableString
NSLog(@"String1:%@",String1);
----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给定的字符串 - (NSRange) rangeOfString: (NSString *) aString,这一点前面在串中搜索子串用到过
NSRange subRange;
subRange = [string1 rangeOfString:@"string A"]; //查找字符串string1中是否包含“string A”。返回NSRange类型。
if(subRange.location == NSNotFound)
NSLog(@"String not found ");
else NSLog(@"string is at index %lu, length is %lu", subRange.location, subRange.length);
NSDate
NSCalendarDate
NSCalendarDate对象包含了日期和时间、时区以及一个带有格式的字符串,它从NSDate继承而来。
NSCalendarDate对象是immutable的,一旦被创建,无法修改其中的时间和日期,当然可以修改那个带格式的字符串和时区。
以下是常用方法:
+(id)calendarDate; //创建当前日期和时间以及默认格式的NSCalendarDate对象,时区为机器设置好的时区。
+(id)dateWithYear:(int)year
month:(unsigned)month
day:(unsigned)day
hour:(unsigned)hour
minute:(unsigned)minute
second:(unsigned)second
timeZone:(NSTimeZone *)aTimeZone
-(int)dayOfCommonEra; //得到从公元1年算起,有多少天
-(int)dayOfMonth; //返回是月的第几天(1-31)
-(int)dayOfWeek; //返回是周的第几天 (0-6)
-(int)dayOfYear; //返回是年的第几天(1-366)
-(int)hourOfDay; // 返回是日的第几个小时(0-23)
-(void)setCalendarFormate:(NSString *)format
--------创建NSCalendarDate对象--------
NSCalendarDate *now;
now = [NSCalendarDate calendarDate];
NSTimeZone *pacific = [NSTimeZone timeZoneWithName:@"PST"];
NSCalendarDate *hotTime = [NSCalendarDate dateWithYear:2011 month:2 day:3 hour:14 minute:0 second:0 timeZone:pacific];
NSData
使用文件时,需要频繁地将数据读入一个临时存储区,它通常成为缓冲区。
NSData类提供了一种简单的方式,它用来设置缓冲区、将文件的内容读入缓冲区,或将缓冲区的内容写到一个文件。
对于32位应用程序,NSDATA缓存区最多可以存储2GB的数据。
我们既可定义不变缓冲区(NSData类),也可定义可变的缓冲区(NSMutableData类)。
下面代码展示了如何将文件的内容读入内存缓冲区,然后再将缓冲区的内容写入到另一个文件中。
NSData *fileData; NSFileManager *fileManager = [[NSFileManager alloc]init]; fileData = [fileManager contentsAtPath:path]; [fileManager createFileAtPath:path2 contents:fileData attributes:nil]; //采用默认的属性值
类型转换 NSData -> NSString:
NSString *strData = [[NSString alloc]initWithData:fileData encoding:NSASCIIStringEncoding];
类型转换 NSString -> NSData:
NSData *fileData2 = [strData dataUsingEncoding:NSUTF8StringEncoding];
NSMutableData