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MSPullToRefreshController.m
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MSPullToRefreshController.m
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//
// MSPullToRefreshController.m
//
// Created by John Wu on 3/5/12.
// Copyright (c) 2012 TFM. All rights reserved.
//
#import "MSPullToRefreshController.h"
@interface PurchaseStatsMSPullToRefreshController ()
@property (nonatomic, assign) MSRefreshingDirections refreshingDirections;
@property (nonatomic, assign) MSRefreshableDirections refreshableDirections;
@property (nonatomic, weak) id <PurchaseStatsMSPullToRefreshDelegate> delegate;
- (void) _checkOffsetsForDirection:(MSRefreshDirection)direction change:(NSDictionary *)change;
@end
@implementation PurchaseStatsMSPullToRefreshController{
// the main object
UIScrollView *_scrollView;
// used internally to capture the did end dragging state
BOOL _wasDragging;
}
#pragma mark - Object Life Cycle
- (id) initWithScrollView:(UIScrollView *)scrollView delegate:(id <PurchaseStatsMSPullToRefreshDelegate>)delegate {
self = [super init];
if (self) {
// set ivars
_delegate = delegate;
_scrollView = scrollView;
// observe the contentOffset. NSKeyValueObservingOptionPrior is CRUCIAL!
[_scrollView addObserver:self forKeyPath:@"contentOffset" options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld | NSKeyValueObservingOptionPrior context:NULL];
}
return self;
}
- (void) dealloc {
// basic clean up
[_scrollView removeObserver:self forKeyPath:@"contentOffset"];
}
#pragma mark - KVO
- (void) observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
if ([keyPath isEqualToString:@"contentOffset"]) {
// for each direction, check to see if refresh sequence needs to be updated.
for (MSRefreshDirection direction = MSRefreshDirectionTop; direction <= MSRefreshDirectionRight; direction++) {
BOOL canRefresh = [_delegate pullToRefreshController:self canRefreshInDirection:direction];
if (canRefresh)
[self _checkOffsetsForDirection:direction change:change];
}
_wasDragging = _scrollView.dragging;
}
}
#pragma mark - Public Methods
- (void) startRefreshingDirection:(MSRefreshDirection)direction {
[self startRefreshingDirection:direction animated:NO];
}
- (void) startRefreshingDirection:(MSRefreshDirection)direction animated:(BOOL)animated {
MSRefreshingDirections refreshingDirection = MSRefreshingDirectionNone;
MSRefreshableDirections refreshableDirection = MSRefreshableDirectionNone;
UIEdgeInsets contentInset = _scrollView.contentInset;
CGPoint contentOffset = CGPointZero;
CGFloat refreshingInset = [_delegate pullToRefreshController:self refreshingInsetForDirection:direction];
CGFloat contentSizeArea = _scrollView.contentSize.width*_scrollView.contentSize.height;
CGFloat frameArea = _scrollView.frame.size.width*_scrollView.frame.size.height;
CGSize adjustedContentSize = contentSizeArea < frameArea ? _scrollView.frame.size : _scrollView.contentSize;
switch (direction) {
case MSRefreshDirectionTop:
refreshableDirection = MSRefreshableDirectionTop;
refreshingDirection = MSRefreshingDirectionTop;
contentInset = UIEdgeInsetsMake(refreshingInset, contentInset.left, contentInset.bottom, contentInset.right);
contentOffset = CGPointMake(0, -refreshingInset);
break;
case MSRefreshDirectionLeft:
refreshableDirection = MSRefreshableDirectionLeft;
refreshingDirection = MSRefreshingDirectionLeft;
contentInset = UIEdgeInsetsMake(contentInset.top, refreshingInset, contentInset.bottom, contentInset.right);
contentOffset = CGPointMake(-refreshingInset, 0);
break;
case MSRefreshDirectionBottom:
refreshableDirection = MSRefreshableDirectionBottom;
refreshingDirection = MSRefreshingDirectionBottom;
contentInset = UIEdgeInsetsMake(contentInset.top, contentInset.left, refreshingInset, contentInset.right);
contentOffset = CGPointMake(0, adjustedContentSize.height + refreshingInset);
break;
case MSRefreshDirectionRight:
refreshableDirection = MSRefreshableDirectionRight;
refreshingDirection = MSRefreshingDirectionRight;
contentInset = UIEdgeInsetsMake(contentInset.top, contentInset.left, contentInset.bottom, refreshingInset);
contentOffset = CGPointMake(adjustedContentSize.width + refreshingInset, 0);
break;
default:
break;
}
if (animated) {
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:0.2];
}
_scrollView.contentInset = contentInset;
_scrollView.contentOffset = contentOffset;
if (animated) {
[UIView commitAnimations];
}
self.refreshingDirections |= refreshingDirection;
self.refreshableDirections &= ~refreshableDirection;
if ([_delegate respondsToSelector:@selector(pullToRefreshController:didEngageRefreshDirection:)]) {
[_delegate pullToRefreshController:self didEngageRefreshDirection:direction];
}
}
- (void) finishRefreshingDirection:(MSRefreshDirection)direction {
[self finishRefreshingDirection:direction animated:NO];
}
- (void) finishRefreshingDirection:(MSRefreshDirection)direction animated:(BOOL)animated {
MSRefreshingDirections refreshingDirection = MSRefreshingDirectionNone;
UIEdgeInsets contentInset = _scrollView.contentInset;
switch (direction) {
case MSRefreshDirectionTop:
refreshingDirection = MSRefreshingDirectionTop;
contentInset = UIEdgeInsetsMake(0, contentInset.left, contentInset.bottom, contentInset.right);
break;
case MSRefreshDirectionLeft:
refreshingDirection = MSRefreshingDirectionLeft;
contentInset = UIEdgeInsetsMake(contentInset.top, 0, contentInset.bottom, contentInset.right);
break;
case MSRefreshDirectionBottom:
refreshingDirection = MSRefreshingDirectionBottom;
contentInset = UIEdgeInsetsMake(contentInset.top, contentInset.left, 0, contentInset.right);
break;
case MSRefreshDirectionRight:
refreshingDirection = MSRefreshingDirectionRight;
contentInset = UIEdgeInsetsMake(contentInset.top, contentInset.left, contentInset.bottom, 0);
break;
default:
break;
}
if (animated) {
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:0.2];
}
_scrollView.contentInset = contentInset;
if (animated) {
[UIView commitAnimations];
}
self.refreshingDirections &= ~refreshingDirection;
}
#pragma mark - Private Methods
- (void) _checkOffsetsForDirection:(MSRefreshDirection)direction change:(NSDictionary *)change {
// define some local ivars that disambiguates according to direction
CGPoint oldOffset = [[change objectForKey:NSKeyValueChangeOldKey] CGPointValue];
MSRefreshingDirections refreshingDirection = MSRefreshingDirectionNone;
MSRefreshableDirections refreshableDirection = MSRefreshableDirectionNone;
BOOL canEngage = NO;
UIEdgeInsets contentInset = _scrollView.contentInset;
CGFloat refreshableInset = [_delegate pullToRefreshController:self refreshableInsetForDirection:direction];
CGFloat refreshingInset = [_delegate pullToRefreshController:self refreshingInsetForDirection:direction];
CGFloat contentSizeArea = _scrollView.contentSize.width*_scrollView.contentSize.height;
CGFloat frameArea = _scrollView.frame.size.width*_scrollView.frame.size.height;
CGSize adjustedContentSize = contentSizeArea < frameArea ? _scrollView.frame.size : _scrollView.contentSize;
switch (direction) {
case MSRefreshDirectionTop:
refreshingDirection = MSRefreshingDirectionTop;
refreshableDirection = MSRefreshableDirectionTop;
canEngage = oldOffset.y < - refreshableInset;
contentInset = UIEdgeInsetsMake(refreshingInset, contentInset.left, contentInset.bottom, contentInset.right);
break;
case MSRefreshDirectionLeft:
refreshingDirection = MSRefreshingDirectionLeft;
refreshableDirection = MSRefreshableDirectionLeft;
canEngage = oldOffset.x < -refreshableInset;
contentInset = UIEdgeInsetsMake(contentInset.top, refreshingInset, contentInset.bottom, contentInset.right);
break;
case MSRefreshDirectionBottom:
refreshingDirection = MSRefreshingDirectionBottom;
refreshableDirection = MSRefreshableDirectionBottom;
canEngage = (oldOffset.y + _scrollView.frame.size.height - adjustedContentSize.height > refreshableInset);
contentInset = UIEdgeInsetsMake(contentInset.top, contentInset.left, refreshingInset, contentInset.right);
break;
case MSRefreshDirectionRight:
refreshingDirection = MSRefreshingDirectionRight;
refreshableDirection = MSRefreshableDirectionRight;
canEngage = oldOffset.x + _scrollView.frame.size.width - adjustedContentSize.width > refreshableInset;
contentInset = UIEdgeInsetsMake(contentInset.top, contentInset.left, contentInset.bottom, refreshingInset);
break;
default:
break;
}
if (!(self.refreshingDirections & refreshingDirection)) {
// only go in here if the requested direction is enabled and not refreshing
if (canEngage) {
// only go in here if user pulled past the inflection offset
if (_wasDragging != _scrollView.dragging && _scrollView.decelerating && [change objectForKey:NSKeyValueChangeNotificationIsPriorKey] && (self.refreshableDirections & refreshableDirection)) {
// if you are decelerating, it means you've stopped dragging.
self.refreshingDirections |= refreshingDirection;
self.refreshableDirections &= ~refreshableDirection;
_scrollView.contentInset = contentInset;
if ([_delegate respondsToSelector:@selector(pullToRefreshController:didEngageRefreshDirection:)]) {
[_delegate pullToRefreshController:self didEngageRefreshDirection:direction];
}
} else if (_scrollView.dragging && !_scrollView.decelerating && !(self.refreshableDirections & refreshableDirection)) {
// only go in here the first time you've dragged past releasable offset
self.refreshableDirections |= refreshableDirection;
if ([_delegate respondsToSelector:@selector(pullToRefreshController:canEngageRefreshDirection:)]) {
[_delegate pullToRefreshController:self canEngageRefreshDirection:direction];
}
}
} else if ((self.refreshableDirections & refreshableDirection) ) {
// if you're here it means you've crossed back from the releasable offset
self.refreshableDirections &= ~refreshableDirection;
if ([_delegate respondsToSelector:@selector(pullToRefreshController:didDisengageRefreshDirection:)]) {
[_delegate pullToRefreshController:self didDisengageRefreshDirection:direction];
}
}
}
}
@end