objective-c中使用nsstring类操作（objective-c中使用nsstring类操作）

一、字符串切割
1、带节点的字符串，如@"讨厌的节点 "我们只想要中间的中文

处理方法：

复制代码代码如下:
NSString *string1 = @"讨厌的节点 ";

/*此处将不想要的字符全部放进characterSet1中，不需另外加逗号或空格之类的，除非字符串中有你想要去除的空格，此处"];

// 将string1按characterSet1中的元素分割成数组

NSArray *array1 = [string1 componentsSeparatedByCharactersInSet:characterSet1];

NSLog(@"array = %@",array1);

for(NSString *string1 in array1)
{
if ([string1 length]>0) {

// 此处string即为中文字符串

NSLog(@"string = %@",string1);
}
}

打印结果：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 2016-01-17 10:55:34.017 string[17634:303] array = ( "", "", "", "\U8ba8\U538c\U7684\U8282\U70b9", "", "", "", "", "", "", "", "", "" ) 2016-01-17 10:55:34.049 string[17634:303] string = 讨厌的节点

2、带空格的字符串，如

@"hello world"去掉空格

复制代码代码如下:
NSString *string2 = @"hello world";

/*处理空格*/

NSCharacterSet *characterSet2 = [NSCharacterSet whitespaceCharacterSet];

// 将string1按characterSet1中的元素分割成数组
NSArray *array2 = [string2 componentsSeparatedByCharactersInSet:characterSet2];

NSLog(@"\narray = %@",array2);

// 用来存放处理后的字符串
NSMutableString *newString1 = [NSMutableString string];

for(NSString *string in array1)
{
[newString1 appendString:string];
}
NSLog(@"newString = %@", newString1);

打印结果：

1 2 3 4 5 6 2016-01-17 11:02:49.656 string[17889:303] array = ( hello, world ) 2016-01-17 11:02:49.657 string[17889:303] newString = helloworld

PS：处理字母等其他元素只需将NSCharacterSet的值改变即可。

复制代码代码如下:
+ (id)controlCharacterSet;

+ (id)whitespaceCharacterSet;

+ (id)whitespaceAndNewlineCharacterSet;

+ (id)decimalDigitCharacterSet;

+ (id)letterCharacterSet;

+ (id)lowercaseLetterCharacterSet;

+ (id)uppercaseLetterCharacterSet;

+ (id)nonBaseCharacterSet;

+ (id)alphanumericCharacterSet;

+ (id)decomposableCharacterSet;

+ (id)illegalCharacterSet;

+ (id)punctuationCharacterSet;

+ (id)capitalizedLetterCharacterSet;

+ (id)symbolCharacterSet;

+ (id)newlineCharacterSet NS_AVAILABLE(10_5, 2_0);

+ (id)characterSetWithRange:(NSRange)aRange;

+ (id)characterSetWithCharactersInString:(NSString *)aString;

+ (id)characterSetWithBitmapRepresentation:(NSData *)data;

+ (id)characterSetWithContentsOfFile:(NSString *)fName;

二、用字符将NSArray中的元素拼接起来

复制代码代码如下:
NSArray *array = [NSArray arrayWithObjects:@"hello",@"world",nil];

//如要用,:等字符串拼接，只需将下面的@" "空格换成@","或@":"即可
NSString *string = [array componentsJoinedByString:@" "];

NSLog(@"string = %@",string);

打印结果：

1	`hello world`

三、截取子串：

这里以获取时间为例，利用NSDate获取到当前时间时，有时候只需要日期或者只需要时间

1、从字符串开头截取到指定的位置，如

复制代码代码如下:
//获取到当前日期时间
NSDate *date = [NSDate date];

//定义日期格式,此处不重点讨论NSDate，故不详细说明，在后面会详细讨论
NSDateFormatter *dateformatter = [[NSDateFormatter alloc] init];

//设置日期格式
[dateformatter setDateFormat:@"YYYY-MM-dd HH:mm"];

//将日期转换成NSString类型
NSString *string = [dateformatter stringFromDate:date];
NSLog(@"\ncurrent = %@",string);

//截取日期substringToIndex
NSString *currentDate = [string substringToIndex:10];

NSLog(@"\ncurrentDate = %@",currentDate);

打印结果：

1 2 3 4 current = 2016-01-1711:12 currentDate = 2016-01-17

2、抽取中间子串-substringWithRange

复制代码代码如下:
//截取月日
NSString *currentMonthAndDate = [string substringWithRange:[NSMakeRange(5, 5)]];

NSLog(@"currentMonthAndDate = %@",currentMonthAndDate);

打印结果：

1	`currentMonthAndDate = 06-27`

3、从某一位置开始截取- substringFromIndex

复制代码代码如下:
//截取时间substringFromIndex
NSString *currentTime = [string substringFromIndex:11];

NSLog(@"\ncurrentTime = %@",currentTime);\

打印结果：

1	`currentTime = 11:25`

四、比较字符串

复制代码代码如下:
NSString *first = @"string";
NSString *second = @"String";

1、判断两个字符串是否相同-isEqualToString方法

复制代码代码如下:
BOOL isEqual = [first isEqualToString:second];

NSLog(@"first is Equal to second:%@",isEqual);

打印结果：

1	`first is Equal to second:0`

2、compare方法比较字符串三个值

复制代码代码如下:

NSOrderedSame//是否相同
NSOrderedAscending//升序，按字母顺序比较，大于为真
NSOrderedDescending//降序，按字母顺序比较，小于为真

BOOL result = [first compare:sencond] == NSOrderedSame;
NSLog(@"result:%d",result);

打印结果：

1	`result:0`

复制代码代码如下:

BOOL result = [first compare:second] == NSOrderedAscending;
NSLog(@"result:%d",result);

打印结果：

1	`result:0`

复制代码代码如下:

BOOL result = [first compare:second] == NSOrderedDecending; NSLog(@"result:%d",result);

打印结果：

1	`result:1`

3、不考虑大小写比较字符串

复制代码代码如下:
BOOL result = [first compare:second
options:NSCaseInsensitiveSearch | NSNumericSearch] == NSOrderedSame;
NSLog(@"result:%d",result);

打印结果：

1	`result:1`

五、改变字符串大小写

复制代码代码如下:
NSString *aString = @"A String";
NSString *string = @"String";
//大写
NSLog(@"aString:%@",[aString uppercaseString]);
//小写
NSLog(@"string:%@",[string lowercaseString]);
//首字母大小写
NSLog(@"string:%@",[string capitalizedString]);

打印结果：

1 2 3 4 5 aString:A STRING string:string string:String

六、在字符串中搜索子串

复制代码代码如下:
NSString *string1 = @"This is a string";
NSString *string2 = @"string";
NSRange range = [string1 rangeOfString:string2];
NSUInteger location = range.location;
NSUInteger leight = range.length;
NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"Location:%li,Leight:%li",location,leight]];
NSLog(@"astring:%@",astring);
[astring release];

打印结果：