我看到很多人写的Search Bar实现比较复杂，而且不一定能够满足需求，这里我介绍一款自制的轻量级Search Bar，非常简单实用
先介绍一个很好用的NSString的分类，作用是取出中文的首字母或者拼音

//拼音
-(NSString*)transformToPinyin{
    NSMutableString *mutableString=[NSMutableString stringWithString:self];
    CFStringTransform((CFMutableStringRef)mutableString,NULL,kCFStringTransformToLatin,false);
    mutableString = (NSMutableString*)[mutableString stringByFoldingWithOptions:NSDiacriticInsensitiveSearch locale:[NSLocale currentLocale]];
   mutableString = [[mutableString stringByReplacingOccurrencesOfString:@" " withString:@""] mutableCopy];
    return mutableString.lowercaseString;
}
//首字母
- (NSString *)transformToPinyinFirstLetter {
    NSMutableString *stringM = [NSMutableString string];
    NSString *temp  =  nil;
    for(int i =0; i < [self length]; i++){
        
        temp = [self substringWithRange:NSMakeRange(i, 1)];
        
        NSMutableString *mutableString=[NSMutableString stringWithString:temp];
        
        CFStringTransform((CFMutableStringRef)mutableString,NULL,kCFStringTransformToLatin,false);
        
        mutableString = (NSMutableString*)[mutableString stringByFoldingWithOptions:NSDiacriticInsensitiveSearch locale:[NSLocale currentLocale]];
        
        mutableString =  [[mutableString substringToIndex:1] mutableCopy];
        
        [stringM appendString:(NSString *)mutableString];
        
    }
    
    return stringM.lowercaseString;
}

接下来就是设置UISearchController了，准备工作是一个全局的UISearchController并初始化，一个模型数组（这个应该都会有），一个用来保存搜索结果的数组

@property(nonatomic,strong)NSArray *modelArray;
@property(nonatomic,strong)NSMutableArray *tempModelArray;
@property(nonatomic,strong)UISearchController *searchController;

设置一下UISearchController的样式,读者可以根据自己的需要设置Placeholder

self.searchController = [[UISearchController alloc]initWithSearchResultsController:nil];
//此处记得遵守UISearchResultsUpdating协议
    self.searchController.searchResultsUpdater = self;
    self.searchController.dimsBackgroundDuringPresentation = false;
    self.searchController.hidesNavigationBarDuringPresentation = NO;
    self.navigationItem.titleView = self.searchController.searchBar;
    [self.searchController.searchBar setPlaceholder:@"输入首字母搜索"];

实现协议方法

-(void)updateSearchResultsForSearchController:(UISearchController *)searchController{
    [self.tempModelArray removeAllObjects];
    NSString *key = [self.searchController.searchBar text].lowercaseString;
    for (（自定义模型类型） *model in self.modelArray) {
//取出首字母
        NSString *firstLetter = [model.(显示字段属性) transformToPinyinFirstLetter];
        if ([firstLetter containsString:key]) {
            [self.tempModelArray addObject:model];
        }
    }
    [self.tableView reloadData];
}

如果读者不是用的UItableView或者UICollectionView,根据协议方法已拿到所需要的数据，读者可以自行刷新UI界面或者其他操作.