字符串操作截取匹配分割替换....

1. 字符串截取

NSString *tempStr = @"123456789";
NSString *tempStr1 = [tempStr substringToIndex:5];//截取下标5之前的字符串
NSLog(@"截取值为 == %@",tempStr1);
NSString *tempStr2 = [tempStr substringFromIndex:5];//截取下标5之后的字符串
NSLog(@"截取值为 == %@",tempStr2);

输出：
2018-12-29 15:24:44.734291+0800 compareDic[9389:721614] 截取值为 == 12345
2018-12-29 15:24:44.734425+0800 compareDic[9389:721614] 截取值为 == 6789

2. 字符串匹配或查找

NSString *tempStr3 = @"https://www.jianshu.com";
NSRange range = [tempStr3 rangeOfString:@"www.ji"];//
NSLog(@"range = %@",NSStringFromRange(range));
tempStr3 = [tempStr3 substringWithRange:range];//匹配当前字符串是否有要查询
的字符
tempStr3 = [tempStr3 substringWithRange:NSMakeRange(3, 5)];//或者可以从第三个字符截取，截取到第五个字符
NSLog(@"匹配值为 == %@",tempStr3);

输出:
2018-12-29 15:58:06.719612+0800 compareDic[9830:831378] range = {8, 6}
2018-12-29 15:58:11.307964+0800 compareDic[9830:831378] 匹配值为 == www.ji
2018-12-29 16:12:20.274156+0800 compareDic[10003:886465] 匹配值为 == ps://

rangeOfString方法意思:
当前字符串https://www.jianshu.com是否包含某个字符www.ji，返回的是NSRange结构体。

typedef struct _NSRange {
    NSUInteger location;
    NSUInteger length;
} NSRange;

其中location意思是在www.ji中的第一个字符w在https://www.jianshu.com第几个位置答案是8。
length意思是www.ji这个要查的字符串的长度，所以是6。

3. 字符串分割

NSString *tempStr = @"https://www.jianshu.com";
NSArray *cutArray = [tempStr componentsSeparatedByString:@"//"];//通过某个字符分割当前字符串，返回值一个数组
NSLog(@"分割字符串值为 = %@",cutArray);

输出：
2018-12-29 16:02:10.741299+0800 compareDic[9885:846881] 分割字符串值为 = (
    "https:",
    "www.jianshu.com"
)

4.字符串替换

NSString *tempStr = @"https://www.jianshu.com";
//OfString不想要的字符串 withString想要 要替换的字符串
NSString *replacedStr = [tempStr stringByReplacingOccurrencesOfString:@"jianshu" withString:@"hangzhou"];
NSLog(@"替换后的字符串 = %@",replacedStr);

输出结果：
2018-12-29 16:19:52.604515+0800 compareDic[10074:907022] 替换后的字符串 = https://www.zhejiang.com

5. 字符串验证

NSString *tempStr = @"https://www.jianshu.com";
//字符串是否已‘http’开头
BOOL valBool = [tempStr hasPrefix:@"http"];
//字符串是否已‘com’结尾
BOOL valBool2 = [tempStr hasSuffix:@"com"];
NSLog(@"valBool = %d",valBool);
NSLog(@"valBool2 = %d",valBool2);

输出：
2018-12-29 16:30:02.814108+0800 compareDic[10201:948064] valBool = 1
2018-12-29 16:30:02.814244+0800 compareDic[10201:948064] valBool2 = 1

6. 字符串改变大小写

NSString *tempStr = @"jiANshu";
//全部转成大写
NSString *changeStr = [tempStr uppercaseString];
//全部转成小写
NSString *changeStr2 = [tempStr lowercaseString];
NSLog(@"大写 = %@",changeStr);
NSLog(@"小写 = %@",changeStr2);

输出：
2018-12-29 16:35:15.880192+0800 compareDic[10292:970824] 大写 = JIANSHU
2018-12-29 16:35:15.880321+0800 compareDic[10292:970824] 小写 = jianshu

7.字符串编码解码

iOS 9.0之后，以前常用的NSString编码的方法stringByAddingPercentEscapesUsingEncoding:弃用了

NSString *tempStr = @"简书";
//此方法意思：会编码字符串中非7-bit ASCII字符 （allowedCharacters）和要忽略的字符集 传的参数
NSString *codeStr = [tempStr stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];
NSString *noCodeStr = [codeStr stringByRemovingPercentEncoding];
NSLog(@"编码 = %@",codeStr);
NSLog(@"解码码 = %@",noCodeStr);

输出：
2018-12-29 16:41:03.717099+0800 compareDic[10406:999421] 编码 = %E7%AE%80%E4%B9%A6
2018-12-29 16:41:03.717278+0800 compareDic[10406:999421] 解码码 = 简书