字串比較 忽略大小寫 iphone

//不考慮大小寫比較字串1
    NSString *astring01 = @"this is a String!";
    NSString *astring02 = @"This is a String!";
    BOOL result = [astring01 caseInsensitiveCompare:astring02] = = NSOrderedSame;    
    NSLog(@"result:%d",result);    
    //NSOrderedDescending判斷兩對象值的大小(按字母順序進行比較，astring02小於astring01為真)

    //不考慮大小寫比較字串2
    NSString *astring01 = @"this is a String!";
    NSString *astring02 = @"This is a String!";
    BOOL result = [astring01 compare:astring02
                            options:NSCaseInsensitiveSearch | NSNumericSearch] = = NSOrderedSame;    
    NSLog(@"result:%d",result);    

    //NSCaseInsensitiveSearch:不區分大小寫比較 NSLiteralSearch:進行完全比較，區分大小寫 NSNumericSearch:比較字串的字元個數，而不是字元值。