Objectvie-C之 NSString 处理技巧

摘要： NSArray中元素拼接成NSString, NSString抽取子串, NSString比较字符串, NSString改变字符串大小写,NSString搜索子串

一、用字符将NSArray中的元素拼接起来

1NSArray *array = [NSArray arrayWithObjects:@"hello",@"world",nil];

2 

3//如要用,:等字符串拼接，只需将下面的@" "空格换成@","或@":"即可

4NSString *string = [array componentsJoinedByString:@" "];

5 

6NSLog(@"string = %@",string);

打印结果：hello world

二、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

01//获取到当前日期时间   

02NSDate *date = [NSDate date];

03         

04//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      

05NSDateFormatter *dateformatter = [[NSDateFormatter alloc] init];

06         

07//设置日期格式       

08[dateformatter setDateFormat:@"YYYY-MM-dd HH:mm"];

09         

10//将日期转换成NSString类型     

11NSString *string = [dateformatter stringFromDate:date];

12NSLog(@"\ncurrent = %@",string);

13                

14//截取日期substringToIndex

15NSString *currentDate = [string substringToIndex:10];

16                 

17NSLog(@"\ncurrentDate = %@",currentDate);

打印结果：

current = 2013-06-27 11:12

currentDate = 2013-06-27

②抽取中间子串-substringWithRange

1//截取月日

2NSString *currentMonthAndDate = [string substringWithRange:[NSMakeRange(5, 5)]];

3         

4NSLog(@"currentMonthAndDate = %@",currentMonthAndDate);

打印结果：

currentMonthAndDate = 06-27

③从某一位置开始截取- substringFromIndex

1//截取时间substringFromIndex

2NSString *currentTime = [string substringFromIndex:11];

3         

4NSLog(@"\ncurrentTime = %@",currentTime);

打印结果：

currentTime = 11:25

三、比较字符串

1NSString *first = @"string";

2NSString *second = @"String";

①判断两个字符串是否相同-isEqualToString方法

1BOOL isEqual = [first isEqualToString:second];

2 

3NSLog(@"first is Equal to second:%@",isEqual);

打印结果：

first is Equal to second:0

②compare方法比较字符串

三个值

1NSOrderedSame//是否相同

2NSOrderedAscending//升序，按字母顺序比较，大于为真

3NSOrderedDescending//降序，按字母顺序比较，小于为真

1BOOL result = [first compare:sencond] == NSOrderedSame;   

2NSLog(@"result:%d",result);

打印结果：

result:0 

1BOOL result = [first compare:second] == NSOrderedAscending;   

2NSLog(@"result:%d",result);

打印结果：

result:0

1<b><b>BOOL result = [first compare:second] == NSOrderedDecending; NSLog(@"result:%d",result);</b></b>

打印结果：

result:1

③不考虑大小写比较字符串

1BOOL result = [first compare:second

2                     options:NSCaseInsensitiveSearch | NSNumericSearch] == NSOrderedSame;

3NSLog(@"result:%d",result);

打印结果：

result:1

四、改变字符串大小写

1NSString *aString = @"A String";

2NSString *string = @"String";

3//大写

4NSLog(@"aString:%@",[aString uppercaseString]);

5//小写

6NSLog(@"string:%@",[string lowercaseString]);

7//首字母大小写

8NSLog(@"string:%@",[string capitalizedString]);

打印结果：

aString:A STRING

string:string

string:String

五、在字符串中搜索子串

1NSString *string1 = @"This is a string";

2NSString *string2 = @"string";

3NSRange range = [string1 rangeOfString:string2];

4NSUInteger location = range.location;

5NSUInteger leight = range.length;

6NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"Location:%li,Leight:%li",location,leight]];

7NSLog(@"astring:%@",astring);

8[astring release];

打印结果：

astring:Location:10,Leight:6