iOS之讓UISearchBar搜尋表徵圖和placeholder靠左顯示

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系統UISearchBar:

需求:

兩種方案:

• 找到UISearchBar上的放大鏡表徵圖, 修改Frame. 同時判斷在有無常值內容更改placeholder的顏色.
• 利用UISearchBar的Text有值後, 放大鏡自動靠左特性, 讓UISearchBar設定一個預設的Text, 在點擊UISearchBar開始編輯後, 如果沒有值,設定Text為則@"", 同時還要根據狀態修改placeholderLabel的顏色.(太繁瑣, 不推薦!)

實現代碼:

@interface ViewController () <UISearchBarDelegate>/** xib搜尋方塊 */@property (weak, nonatomic) IBOutlet UISearchBar *searchBar;/** 搜尋圖片(放大鏡) */@property (nonatomic, weak) UIImageView *imgV;@end@implementation ViewController- (void)viewDidAppear:(BOOL)animated{    [super viewDidAppear:animated];    // 尋找放大鏡圖片ImageView    for (UIImageView *imgV in _searchBar.subviews.firstObject.subviews.lastObject.subviews) {        if ([imgV isMemberOfClass:[UIImageView class]]) {            imgV.frame = CGRectMake(8, 7.5, 13, 13);            _imgV = imgV;            [_imgV addObserver:self forKeyPath:@"frame" options:NSKeyValueObservingOptionNew context:nil];        }    }    // 設定searchBar文本顏色    [self updateSeachBar];}- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context{    // 修改放大鏡Frame前, 移除觀察者    [_imgV removeObserver:self forKeyPath:@"frame"];    // 修改Frame    _imgV.frame = CGRectMake(8, 7.5, 13, 13);    // 再次添加觀察者    [_imgV addObserver:self forKeyPath:@"frame" options:NSKeyValueObservingOptionNew context:nil];}#pragma mark -UISearchBarDelegate代理方法- (void)searchBarTextDidBeginEditing:(UISearchBar *)searchBar{    if ([searchBar.text isEqualToString:searchBar.placeholder]) {        // 無文本時, 顯示placeholder        searchBar.text = @"";    }    // 擷取到UISearchBar中UITextField    UITextField *searchField = [searchBar valueForKey:@"_searchField"];    // 開始編輯要修改textColor顏色    searchField.textColor = [UIColor blackColor];    searchField.clearButtonMode = UITextFieldViewModeWhileEditing;}- (void)searchBarTextDidEndEditing:(UISearchBar *)searchBar{    [self updateSeachBar];}#pragma mark -根據常值內容設定searchBar顏色及clearButtonMode- (void)updateSeachBar{    if ([_searchBar.text isEqualToString:@""]) {// 常值內容為空白時        UITextField *searchField = [_searchBar valueForKey:@"_searchField"];        // 修改textColor為placeholderColor        searchField.textColor = [searchField valueForKeyPath:@"_placeholderLabel.textColor"];        searchField.text = searchField.placeholder;        // 去除右側clearButton        searchField.clearButtonMode = UITextFieldViewModeNever;    }}- (void)dealloc{    // 移除觀察者    [_searchBar removeObserver:self forKeyPath:@"frame"];}

 

iOS之讓UISearchBar搜尋表徵圖和placeholder靠左顯示