yoon-boom / SVPullToRefresh

Give pull-to-refresh & infinite scrolling to any UIScrollView with 1 line of code.

Additional Observer Removal Info

I assume current API has been sitting here for long time and can't track the good written fork trackerz. My problem was, UITableView instance in UIViewController and this UIViewController needs dismiss and crashes after invoke - (void)dealloc method that KVO still runs with the keyPath which object were already deallocated. a) tried to call [[NSNotificationCenter defaultCenter] removeObserver:self]; no luck b) tried to remove [[NSNotificationCenter defaultCenter] removeObserver:self.tableView]; no luck c) uncommented to addObserver and removeObserver luck. d) find out the issue this API might adding duplicated observer(s). Since as of now generically can't find duplicate observers, I created NSMutableDicrionary to track unique keyPath.

Besure to dereference observer from callee. For example, your UITableView is using SVPullToRefresh + SVInfiniteScrolling Category. Unsubscribe this before your object (UIViewController) deallocated.

    [self.tableView safelyRemoveObserver:self.tableView object:self.tableView.infiniteScrollingView keyPath:@"contentOffset"];
    [self.tableView safelyRemoveObserver:self.tableView object:self.tableView.infiniteScrollingView keyPath:@"contentSize"];

SVPullToRefresh + SVInfiniteScrolling

These UIScrollView categories makes it super easy to add pull-to-refresh and infinite scrolling fonctionalities to any UIScrollView (or any of its subclass). Instead of relying on delegates and/or subclassing UIViewController, SVPullToRefresh uses the Objective-C runtime to add the following 3 methods to UIScrollView:

- (void)addPullToRefreshWithActionHandler:(void (^)(void))actionHandler;
- (void)addPullToRefreshWithActionHandler:(void (^)(void))actionHandler position:(SVPullToRefreshPosition)position;
- (void)addInfiniteScrollingWithActionHandler:(void (^)(void))actionHandler;

Installation

From CocoaPods

Add pod 'SVPullToRefresh' to your Podfile or pod 'SVPullToRefresh', :head if you're feeling adventurous.

Manually

Important note if your project doesn't use ARC: you must add the -fobjc-arc compiler flag to UIScrollView+SVPullToRefresh.m and UIScrollView+SVInfiniteScrolling.m in Target Settings > Build Phases > Compile Sources.

• Drag the SVPullToRefresh/SVPullToRefresh folder into your project.
• Add the QuartzCore framework to your project.
• Import UIScrollView+SVPullToRefresh.h and/or UIScrollView+SVInfiniteScrolling.h

Usage

(see sample Xcode project in /Demo)

Adding Pull to Refresh

[tableView addPullToRefreshWithActionHandler:^{
    // prepend data to dataSource, insert cells at top of table view
    // call [tableView.pullToRefreshView stopAnimating] when done
}];

or if you want pull to refresh from the bottom

[tableView addPullToRefreshWithActionHandler:^{
    // prepend data to dataSource, insert cells at top of table view
    // call [tableView.pullToRefreshView stopAnimating] when done
} position:SVPullToRefreshPositionBottom];

If you’d like to programmatically trigger the refresh (for instance in viewDidAppear:), you can do so with:

[tableView triggerPullToRefresh];

You can temporarily hide the pull to refresh view by setting the showsPullToRefresh property:

tableView.showsPullToRefresh = NO;

Customization

The pull to refresh view can be customized using the following properties/methods:

@property (nonatomic, strong) UIColor *arrowColor;
@property (nonatomic, strong) UIColor *textColor;
@property (nonatomic, readwrite) UIActivityIndicatorViewStyle activityIndicatorViewStyle;

- (void)setTitle:(NSString *)title forState:(SVPullToRefreshState)state;
- (void)setSubtitle:(NSString *)subtitle forState:(SVPullToRefreshState)state;
- (void)setCustomView:(UIView *)view forState:(SVPullToRefreshState)state;

You can access these properties through your scroll view's pullToRefreshView property.

For instance, you would set the arrowColor property using:

tableView.pullToRefreshView.arrowColor = [UIColor whiteColor];

Adding Infinite Scrolling

[tableView addInfiniteScrollingWithActionHandler:^{
    // append data to data source, insert new cells at the end of table view
    // call [tableView.infiniteScrollingView stopAnimating] when done
}];

If you’d like to programmatically trigger the loading (for instance in viewDidAppear:), you can do so with:

[tableView triggerInfiniteScrolling];

You can temporarily hide the infinite scrolling view by setting the showsInfiniteScrolling property:

tableView.showsInfiniteScrolling = NO;

Customization

The infinite scrolling view can be customized using the following methods:

- (void)setActivityIndicatorViewStyle:(UIActivityIndicatorViewStyle)activityIndicatorViewStyle;
- (void)setCustomView:(UIView *)view forState:(SVInfiniteScrollingState)state;

You can access these properties through your scroll view's infiniteScrollingView property.

Under the hood

SVPullToRefresh extends UIScrollView by adding new public methods as well as a dynamic properties.

It uses key-value observing to track the scrollView's contentOffset.

Credits

SVPullToRefresh is brought to you by Sam Vermette and contributors to the project. If you have feature suggestions or bug reports, feel free to help out by sending pull requests or by creating new issues. If you're using SVPullToRefresh in your project, attribution would be nice.

Big thanks to @seb_morel for his Demistifying the Objective-C runtime talk which really helped for this project.

Hat tip to Loren Brichter for inventing pull-to-refresh.