Basic knowledge of IOS development-fragment 40, basic knowledge of ios-Fragment

Basic knowledge of IOS development-fragment 40, basic knowledge of ios-Fragment

1: Quick Error Reporting tips for Masonry

self.statusLabel = [UILabel new];[self.contentView addSubview:self.statusLabel];MASAttachKeys(self.statusLabel);[self.statusLabel mas_makeConstraints:^(MASConstraintMaker *make) {make.top.equalTo(self.contentView).offset(15.0f);make.left.equalTo(self.contentView).offset(10.f);make.height.equalTo(10);make.bottom.equalTo(self.contentView);}];

Note: MASAttachKeys displays a clear error message;

 

2: Jump to system settings for iOS

Note: To enable the function of redirecting from the application to the system settings page, you must first add prefs to Targets-Info-URL Types-URL Schemes.

Jump to WIFI settings if ([[UIApplication sharedApplication] canOpenURL: [NSURL URLWithString: @ "prefs: root = WIFI"]) {[[UIApplication sharedApplication] openURL: [NSURL URLWithString: @ "prefs: root = WIFI"];} jump to Bluetooth if ([[UIApplication sharedApplication] canOpenURL: [NSURL URLWithString: @ "prefs: root = Bluetooth"]) {[[UIApplication sharedApplication] openURL: [NSURL URLWithString: @ "prefs: root = Bluetooth"];} jump to General if ([[UIApplication sharedApplication] canOpenURL: [NSURL URLWithString: @ "prefs: root = General"]) {[[UIApplication sharedApplication] openURL: [NSURL URLWithString: @ "prefs: root = General"];} jump to the local if ([[UIApplication sharedApplication] canOpenURL: [NSURLURLWithString: @ "prefs: root = General & path = About"]) {[[UIApplication sharedApplication] openURL: [NSURL URLWithString: @ "prefs: root = General & path = About"];} jump to the target service if ([[UIApplication sharedApplication] canOpenURL: [NSURL URLWithString: @ "prefs: root = LOCATION_SERVICES "]) {[[UIApplication sharedApplication] openURL: [NSURL URLWithString: @" prefs: root = LOCATION_SERVICES "];} jump to notification if ([[UIApplication sharedApplication] canOpenURL: [NSURL URLWithString: @ "prefs: root = icationications_id"]) {[[UIApplication sharedApplication] openURL: [NSURL URLWithString: @ "prefs: root = icationications_id"];}

3: The UITableView section scrolls with the cell.

Implement the following method of UITableView: # pragma mark-Scroll-(void) scrollViewDidScroll :( UIScrollView *) scrollView {CGFloat sectionHeaderHeight = 40; // fixed section scrolling with cell if (scrollView. contentOffset. y <= sectionHeaderHeight & scrollView. contentOffset. y> = 0) {scrollView. contentInset = UIEdgeInsetsMake (-scrollView. contentOffset. y, 0, 0, 0);} else if (scrollView. contentOffset. y> = sectionHeaderHeight) {scrollView. contentInset = UIEdgeInsetsMake (-sectionHeaderHeight, 0, 0, 0 );}}

 4: How does TableView refresh a specified cell or section?

// Refresh NSIndexSet * indexSet = [[NSIndexSet alloc] initWithIndex: 2] for a section; [tableview reloadSections: indexSet withRowAnimation: UITableViewRowAnimationAutomatic]; // refresh NSIndexPath * indexPath = [NSIndexPath indexPathForRow: 3 inSection: 0]; [tableView reloadRowsAtIndexPaths: [NSArray arrayWithObjects: indexPath, nil] withRowAnimation: parent];

5: TableView another method to implement the effect of blank rows

Increase the total number of items, and then calculate the remainder

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{    static NSString *CELL_ID2 = @"SOME_STUPID_ID2";    // even rows will be invisible    if (indexPath.row % 2 == 1)    {        UITableViewCell * cell2 = [tableView dequeueReusableCellWithIdentifier:CELL_ID2];        if (cell2 == nil)        {            cell2 = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault                                          reuseIdentifier:CELL_ID2];            [cell2.contentView setAlpha:0];            [cell2 setUserInteractionEnabled:NO]; // prevent selection and other stuff        }        return cell2;    }    [ccTableView setBackgroundColor:[UIColor clearColor]];    cardsCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cardsCell"];    if(cell == nil){      NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:@"cardsCell" owner:self options:nil];      cell = [topLevelObjects objectAtIndex:0];    }     // Use indexPath.row/2 instead of indexPath.row for the visible section to get the correct datasource index (number of rows is increased to add the invisible rows)        NSString *nmCard = [[self.cards valueForKeyPath:@"cards.name"] objectAtIndex:(indexPath.row/2)];        cell.descCardLabel.text = nmCard;      return cell;    }- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{    // two times minus one (invisible at even rows => visibleCount == invisibleCount+1)    return [[self.cards valueForKeyPath:@"cards"] count] * 2 - 1;}- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath{    if (indexPath.row % 2 == 1)        return 40;    return 162;}

6: Scroll TableView to the specified position

- (void)scrollToRowAtIndexPath:(NSIndexPath *)indexPath atScrollPosition:(UITableViewScrollPosition)scrollPosition animated:(BOOL)animated

typedef enum {    UITableViewScrollPositionNone,    UITableViewScrollPositionTop,    UITableViewScrollPositionMiddle,    UITableViewScrollPositionBottom } UITableViewScrollPosition;