//NSString的初始化
NSString *str1=[[NSString alloc]init];
//1.创建
//快速创建
NSString *str2=@"11";
//alloc方法初始化，这种方法已经被快速创建方法取代,此处警告就是因为这种方法已经不用
NSString *str3=[[NSString alloc]initWithString:@"1"];
//格式化符创建
NSString *str4=[[NSString alloc]initWithFormat:@"1"];
NSString *str5=[[NSString alloc]initWithFormat:@"1"];
//2.比较两个字符串是否相等；相等是NSOrderedSame，升序NSOrderedAscending；此时比较两个字符串的大小是不分大小写
NSComparisonResult result=[str4 caseInsensitiveCompare:str5];
if (result==NSOrderedAscending) {
NSLog(@"升序");
}
if (result==NSOrderedDescending) {
NSLog(@"降序");
}
if (result==NSOrderedSame) {
NSLog(@"相等");
}
//不区分大小写NSCaseInsensitiveSearch、NSNumericSearch
NSString *s1=@"aaaa";
NSString *s2=@"AAAA";
NSComparisonResult result1=[s1 compare:s2 options:NSCaseInsensitiveSearch|NSNumericSearch];
if (result1==NSOrderedAscending) {
NSLog(@"---升序");
}
if (result1==NSOrderedDescending) {
NSLog(@"---降序");
}
if (result1==NSOrderedSame) {
NSLog(@"----相等");
}
//区分大小写NSLiteralSearch
NSString *s3=@"aaaa";
NSString *s4=@"AAAA";
NSComparisonResult result2=[s3 compare:s4 options:NSLiteralSearch];
if (result2==NSOrderedAscending) {
NSLog(@"---升序");
}
if (result2==NSOrderedDescending) {
NSLog(@"---降序");
}
if (result2==NSOrderedSame) {
NSLog(@"----相等");
}
//在这里str4=str5比较的是两个字符串的地址,两个字符串的地址是不相等的
if (str4 == str5) {
NSLog(@"比较地址");
}
//3.字符串的访问
//分割字符串componentsSeparatedByString
NSString *str6=@"ssajjakkall";
NSArray *arr1=[str6 componentsSeparatedByString:@"a"];
NSLog(@"%@",arr1);
//访问指定的字符串
NSString *str7=@"abcdsdf";
char s=[str7 characterAtIndex:1];
NSLog(@"%c",s);
//4.字符串的截取
//截取到指定的字符串,此方法是把从0~2的字符删去
NSString *str8=[str7 substringFromIndex:2];
NSLog(@"%@",str8);
//从指定位置接取
NSString *str9=[str7 substringToIndex:2];
NSLog(@"%@",str9);
//范围截取
//NSMakeRange(位置, 截取长度);
NSRange r=NSMakeRange(0, 2);
NSString *str10=[str7 substringWithRange:r];
NSLog(@"%@",str10);
//5.拼接字符串
//stringWithFormate方法
NSString *str11=@"ab";
NSString *str12=@"cd";
NSString *str13=[NSString stringWithFormat:@"%@%@",str11,str12];
NSLog(@"%@",str13);
//stringByAppendingString方法
NSString *str14=[str11 stringByAppendingString:str12];
NSLog(@"%@",str14);
//stringByAppendingFormat方法
NSString *str15=[str11 stringByAppendingFormat:@"%@",str12];
NSLog(@"%@",str15);
//6查找替换
//查找
NSString *email=@"11111111@qq.com";
NSString *str16=@"@qq.com";
NSRange range=[email rangeOfString:str16];
NSLog(@"range.location=%lu,range.length=%lu",range.location,range.length);
//替换
NSString *str17=@"1234aaa";
NSString *str18=[str17 stringByReplacingOccurrencesOfString:str17 withString:@"abcdd"];
NSLog(@"%@",str18);