iOS NSString 属性

 

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:

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

//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 = 2016-01-1711:12
currentDate = 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:

currentTime = 11:25

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:

result:0

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

打印结果:

result:0
BOOL result = [first compare:second] == NSOrderedDecending; NSLog(@\"result:%d\",result);

 

打印结果:

result:1

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:

result:1

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 STRING
string:string
string: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);

 

打印结果:

astring:Location:10,Leight:6

 

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