一、字符串切割
1、带节点的字符串，如@"<p>讨厌的节点<br/></p>"我们只想要中间的中文
处理方法：
NSString *string1 = @"<p>讨厌的节点<br/></p>";
/*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< p /等都是单独存在，不作为整个字符*/
NSCharacterSet *characterSet1 = [NSCharacterSet characterSetWithCharactersInString:@"<p/brh>"];
// 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 = 2016-01-1711:12
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：
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 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);
[astring release];
打印结果：
astring:Location:10,Leight:6
