一、NSString
1、将NSData转化为NSString
NSString* str = [[NSString alloc] initWithData:response encoding:NSUTF8StringEncoding];
2、将NSString 转化为NSData
- (NSData *)dataUsingEncoding:(NSStringEncoding)encoding;
3、载一个字符串中删除一个字符或字符串
[_display deleteCharactersInRange:NSMakeRange(index_of_char_to_remove, 1)];
4、从文件读取字符串:initWithContentsOfFile方法
NSString *path = @"***.text";
NSString *astring = [[NSString alloc] initWithContentsOfFile:path];
5、写字符串到文件:writeToFile方法
NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];
NSString *path = @"astring.text";
[astring writeToFile: path atomically: YES];
6、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)
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
7、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
8、在字符串中搜索子串
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]];
9、截取子串
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);
10、获取扩展名：[Path pathExtension]
11、判断是否以某个字符串开始或结尾
-(BOOL) hasPrefix:(NSString *) aString; //开头
-(BOOL) hasSuffix:(NSString *) aString; //结尾
二、NSMutableString
1、给字符串分配容量
NSMutableString *String;
String = [NSMutableString stringWithCapacity:40];
2、在已有字符串后面添加字符
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"]];
3、在已有字符串中按照所给出范围和长度删除字符
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 deleteCharactersInRange:NSMakeRange(0, 5)];
4、在已有字符串后面在所指定的位置中插入给出的字符串
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 insertString:@"Hi! " atIndex:0];
5、将已有的空符串换成其它的字符串
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 setString:@"Hello Word!"];
6、按照所给出的范围，和字符串替换的原有的字符
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"];
7、判断字符串内是否还包含别的字符串(前缀，后缀)
1>、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");
2>、查找字符串某处是否包含其它字符串 - (NSRange) rangeOfString: (NSString *) aString，这一点前面在串中搜索子串用到过;
三、字符串与数组的相互转化
1、从字符串分割到数组
NSString *string = [[NSString alloc] initWithString:@"One,Two,Three,Four"];
NSArray *array = [string componentsSeparatedByString:@","];
2、从数组合并元素到字符串
NSArray *array = [[NSArray alloc] initWithObjects:@"One",@"Two",@"Three",@"Four",nil];
NSString *string = [array componentsJoinedByString:@","];
四、字符串比较方法对比
1>、isEqualToString :可以用来比较接收方和当作参数传递来的字符串的内容是否相同，返回yes和no
2>、==:只判断指针数值，而不是它们所指向的内容
3>、compare:比较两个字符串。区分大小写
compare将接收对象和传递来的字符串逐个字符的进行比较，它返回一个NSComparisonResult(枚举类型)来显示结果。
typedef enum _NSComparisonResult{
NSOrderedAscending=-1;
NSOrderedsame;
NSOrderedDescending;
} NSComparisonResult;
4>、 compare: options: ( options 是一个位掩码，可以使用|添加选项标记选项 )
options选项：
NSCaseInsensitiveSearch:不区分大小写字符
NSLiteralSearch:进行完全比较，区分大小写
NSNumbericSearch:比较字符串的字符个数，而不是字符值
五、字典转化为字符串
NSError *parseError = nil;
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dict options:NSJSONWritingPrettyPrinted error:&parseError];
NSString *str = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"提示" message:str delegate:self cancelButtonTitle:@"不，谢了" otherButtonTitles:@"瞅瞅去", nil];
[alert show];
匹配字符串头或尾
hasPrefixe 匹配字符串头
haSuffix 匹配字符串的尾巴
NSString *string1 = @"卡拉是条狗";
NSString *string2 = @"狗狗叫卡拉";
//字符串以开头比较
if([string1 hasPrefix:@"卡拉"])
{
NSLog(@"字符串string1以卡拉开头");
}
//字符串以结尾比较
if([string2 hasSuffix:@"卡拉"])
{
NSLog(@"string2字符串以卡拉结尾");
}