在IOS开发过程中，我们可能会遇到许多关于字符串的编程，字符串是一种常见的数据类型，以下是武林技术频道小编介绍的Objective-C中使用NSString类操作字符串的方法有哪些，一起进入下文了解一下吧！
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：
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
NSCharacterSet *characterSet1 = [NSCharacterSet characterSetWithCharactersInString:@///"
///"];
// 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：
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
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：
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。
+ (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
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：
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
//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：
current = 2016-01-1711:12currentDate = 2016-01-17
2、抽取中间子串-substringWithRange
//截取月日
NSString *currentMonthAndDate = [string substringWithRange:[NSMakeRange(5, 5)]];
NSLog(@///"currentMonthAndDate = %@///",currentMonthAndDate);
打印结果：
currentMonthAndDate = 06-27
3、从某一位置开始截取- substringFromIndex
//截取时间substringFromIndex
NSString *currentTime = [string substringFromIndex:11];
NSLog(@///"////ncurrentTime = %@///",currentTime);////
打印结果：
四、比较字符串
NSString *first = @///"string///";
NSString *second = @///"String///";
1、判断两个字符串是否相同-isEqualToString方法
BOOL isEqual = [first isEqualToString:second];
NSLog(@///"first is Equal to second:%@///",isEqual);
打印结果：
first is Equal to second:0
2、compare方法比较字符串三个值
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：
BOOL result = [first compare:second] == NSOrderedAscending;
NSLog(@///"result:%d///",result);
打印结果：
BOOL result = [first compare:second] == NSOrderedDecending; NSLog(@///"result:%d///",result);
打印结果：
3、不考虑大小写比较字符串
BOOL result = [first compare:second
options:NSCaseInsensitiveSearch | NSNumericSearch] == NSOrderedSame;
NSLog(@///"result:%d///",result);
打印结果：
五、改变字符串大小写
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：
aString:A STRINGstring:stringstring:String
六、在字符串中搜索子串
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：
astring:Location:10,Leight:6
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