Case-insensitive NSString comparison

问题

Using this code I am able to compare string values.

[elementName isEqualToString: @"Response"]

But this compares case-sensitively. Is there a way to compare the string without case sensitivity?

回答1:

There’s a caseInsensitiveCompare: method on NSString, why don’t you read the documentation? The method returns NSComparisonResult:

enum {
   NSOrderedAscending = -1,
   NSOrderedSame,
   NSOrderedDescending
};
typedef NSInteger NSComparisonResult;

…ah, sorry, just now I realized you are asking for case sensitive equality. (Why don’t I read the question? :-) The default isEqual: or isEqualToString: equality should already be case sensitive, what gives?

回答2:

Here's the code you would need to compare a string without caring about whether it's lowercase or uppercase:

if ([elementName caseInsensitiveCompare:@"Response"]==NSOrderedSame)
{
    //  Your "elementName" variable IS "Response", "response", "reSPonse", etc
    //  
}

回答3:

Actually isEqualToString: works with case sensitive ability. as:

[elementName isEqualToString: @"Response"];

if you want to ask for case insensitive compare then here is the code:

You can change both comparable string to lowerCase or uppercase, and can compare as:

NSString *tempString = @"Response";
NSString *string1 = [elementName lowercaseString];
NSString *string2 =  [tempString lowercaseString];

//The same code changes both strings in lowerCase.
//Now You Can compare

if([string1 isEqualToString:string2])
{

//Type your code here

}

回答4:

NSString *string1 = @"stringABC";
NSString *string2 = @"STRINGDEF";
NSComparisonResult result = [string1 caseInsensitiveCompare:string2];

if (result == NSOrderedAscending) {
  NSLog(@"string1 comes before string2");
} else if (result == NSOrderedSame) {
  NSLog(@"We're comparing the same string");
} else if (result == NSOrderedDescending) {
   NSLog(@"string2 comes before string1");
}

来源：https://stackoverflow.com/questions/4488877/case-insensitive-nsstring-comparison