如果你想要更多的控制，而不仅仅是不区分大小写，另一个选择是:

[someString compare:otherString options:NSCaseInsensitiveSearch];

数字搜索和变音符不敏感是两个方便的选择。

- (NSComparisonResult)caseInsensitiveCompare:(NSString *)aString

NSMutableArray *arrSearchData;  
NSArray *data=[arrNearByData objectAtIndex:i];
NSString *strValue=[NSString stringWithFormat:@"%@", [data valueForKey:@"restName"]];
NSRange r = [strValue rangeOfString:key options:NSCaseInsensitiveSearch];

if(r.location != NSNotFound)
{
     [arrSearchData addObject:data];
}

swift的替代解决方案:

要使两者都大写:

e.g:

if ("ABcd".uppercased() == "abcD".uppercased()){
}

或使两者都小写:

e.g:

if ("ABcd".lowercased() == "abcD".lowercased()){
}

一种新的方法。iOS 8

let string: NSString = "Café"
let substring: NSString = "É"

string.localizedCaseInsensitiveContainsString(substring) // true

if( [@"Some String" caseInsensitiveCompare:@"some string"] == NSOrderedSame ) {
  // strings are equal except for possibly case
}

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