ios fix UIRefreshControl bug

NS_CLASS_AVAILABLE_IOS(6_0)   UIRefreshControl
有个毛病有时会出bug  动画下拉就不动了，这里给出修复处理：

@interface UICollectionView (FixRefreshControlJump)

@end

#import "UICollectionView+FixRefreshControlJump.h"

#import <objc/runtime.h>

@implementation UICollectionView (FixRefreshControlJump)
+ (void)load

{

    Method originMethod = class_getInstanceMethod([UICollectionView class], @selector(setContentInset:));

    Method newMethod = class_getInstanceMethod([UICollectionView class], @selector(setNewContentInset:));

    method_exchangeImplementations(originMethod, newMethod);
UIRefreshControl

}
- (void)setNewContentInset:(UIEdgeInsets)contentInset

{

    if (self.tracking) {

        CGFloat diff = contentInset.top - self.contentInset.top;

        CGPoint translation = [self.panGestureRecognizer translationInView:self];

        translation.y -= diff * 3.0 / 2.0;

        [self.panGestureRecognizer setTranslation:translation inView:self];

    }

    if ([self respondsToSelector:@selector(setNewContentInset:)]) {

        [self setNewContentInset:contentInset];

    }

}
@end

通过 method_exchangeImplementations swzing的方式处理问题

推荐阅读：

http://www.cnblogs.com/kesalin/archive/2012/01/05/objc_method_swizzling.html