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
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