iOS-ios 上提加载更多怎么保持状态栏在底部的，求原理

Question

在做一个小应用的时候用到了“下拉刷新，上拉加载更多”的效果，但是怎么保持状态栏始终在tableview底部，（用了EGORefreshTableHeaderView插件），我知道需要更改图片的方向和laber的位置，但是laber怎么保持在底部呢？在网上有看到相关代码，但是没有原理，不是很理解，求大神指教原理。。最好带上代码吧，我是菜鸟》》》谢谢了

Answer 1

每个tableview有一个footerView，代表tableview的最下面的部分，用这个footerview来做上提加载更多，当没有下一页的时候隐藏这个footerview就可以了。

//
// LoadMoreTableFooterView.h
// KlipTao
//
// Created by Wang Dave on 11-11-13.
// Copyright (c) 2011年 DaveDev. All rights reserved.
//

#import <UIKit/UIKit.h>
#import <QuartzCore/QuartzCore.h>

typedef enum{
LoadMorePulling = 3,
LoadMoreNormal = 4,
LoadMoreLoading = 5,
} LoadMoreState;
@protocol LoadMoreTableFooterViewDelegate;
@interface LoadMoreTableFooterView : UIView
{

id _delegate;
LoadMoreState _state;

UILabel *_statusLabel;
CALayer *_arrowImage;
UIActivityIndicatorView *_activityView;
}

@property(nonatomic,assign) id <LoadMoreTableFooterViewDelegate> delegate;

(void)loadMoreScrollViewDidScroll:(UIScrollView *)scrollView;
(void)loadMoreshScrollViewDidEndDragging:(UIScrollView *)scrollView;
(void)loadMoreshScrollViewDataSourceDidFinishedLoading:(UIScrollView *)scrollView;

@end
@protocol LoadMoreTableFooterViewDelegate
- (void)loadMoreTableFooterDidTriggerRefresh:(LoadMoreTableFooterView*)view;
- (BOOL)loadMoreTableFooterDataSourceIsLoading:(LoadMoreTableFooterView*)view;

@end

//
// LoadMoreTableFooterView.m
// KlipTao
//
// Created by Wang Dave on 11-11-13.
// Copyright (c) 2011年 DaveDev. All rights reserved.
//
#define LoadMoreViewHight 60.0f
#import "LoadMoreTableFooterView.h"
#define TEXT_COLOR [UIColor darkGrayColor]
//[UIColor colorWithRed:87.0/255.0 green:108.0/255.0 blue:137.0/255.0 alpha:1.0]
#define FLIP_ANIMATION_DURATION 0.18f
@interface LoadMoreTableFooterView (Private)
- (void)setState:(LoadMoreState)aState;
@end
@implementation LoadMoreTableFooterView
@synthesize delegate=_delegate;
- (id)initWithFrame:(CGRect)frame {
self = [super initWithFrame: frame];
if (self) {

self.autoresizingMask = UIViewAutoresizingFlexibleWidth;
//self.backgroundColor = [UIColor colorWithRed:226.0/255.0 green:231.0/255.0 blue:237.0/255.0 alpha:1.0];

// UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0.0f, LoadMoreViewHight - 30.0f, self.frame.size.width, 20.0f)];
// label.autoresizingMask = UIViewAutoresizingFlexibleWidth;
// label.font = [UIFont systemFontOfSize:12.0f];
// label.textColor = TEXT_COLOR;
// label.shadowColor = [UIColor colorWithWhite:0.9f alpha:1.0f];
// label.shadowOffset = CGSizeMake(0.0f, 1.0f);
// label.backgroundColor = [UIColor clearColor];
// label.textAlignment = UITextAlignmentCenter;
// [self addSubview:label];
// _lastUpdatedLabel=label;
// [label release];

UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0.0f, LoadMoreViewHight - 48.0f, self.frame.size.width, 20.0f)];
label.autoresizingMask = UIViewAutoresizingFlexibleWidth;
label.font = [UIFont boldSystemFontOfSize:13.0f];
label.textColor = TEXT_COLOR;
label.shadowColor = [UIColor colorWithWhite:0.9f alpha:1.0f];
label.shadowOffset = CGSizeMake(0.0f, 1.0f);
label.backgroundColor = [UIColor clearColor];
label.textAlignment = UITextAlignmentCenter;
[self addSubview:label];
_statusLabel=label;
[label release];

CALayer *layer = [CALayer layer];
layer.frame = CGRectMake(25.0f, LoadMoreViewHight - LoadMoreViewHight, 30.0f, 55.0f);
layer.contentsGravity = kCAGravityResizeAspect;
layer.contents = (id)[UIImage imageNamed:@"blueArrow.png"].CGImage;

#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 40000
if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)]) {
layer.contentsScale = [[UIScreen mainScreen] scale];
}
#endif

[[self layer] addSublayer:layer];
_arrowImage=layer;

UIActivityIndicatorView *view = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
view.frame = CGRectMake(25.0f, LoadMoreViewHight - 38.0f, 20.0f, 20.0f);
[self addSubview:view];
_activityView = view;
[view release];

[self setState:LoadMoreNormal];

}

return self;

}

(void)setState:(LoadMoreState)aState{

switch (aState) {
case LoadMorePulling:

_statusLabel.text = NSLocalizedString(@"松开即可加载更多...", @"松开即可加载更多...");
[CATransaction begin];
[CATransaction setAnimationDuration:FLIP_ANIMATION_DURATION];
_arrowImage.transform = CATransform3DMakeRotation((M_PI / 180.0) * 180.0f, 0.0f, 0.0f, 1.0f);
[CATransaction commit];

break;
case LoadMoreNormal:

if (_state == LoadMorePulling) {
[CATransaction begin];
[CATransaction setAnimationDuration:FLIP_ANIMATION_DURATION];
_arrowImage.transform = CATransform3DIdentity;
[CATransaction commit];
}

_statusLabel.text = NSLocalizedString(@"上拉即可加载更多...", @"上拉即可加载更多...");
[_activityView stopAnimating];
[CATransaction begin];
[CATransaction setValue:(id)kCFBooleanTrue forKey:kCATransactionDisableActions];
_arrowImage.hidden = NO;
_arrowImage.transform = CATransform3DIdentity;
[CATransaction commit];

//[self refreshLastUpdatedDate];

break;
case LoadMoreLoading:

_statusLabel.text = NSLocalizedString(@"加载中...", @"加载中...");
[_activityView startAnimating];
[CATransaction begin];
[CATransaction setValue:(id)kCFBooleanTrue forKey:kCATransactionDisableActions];
_arrowImage.hidden = YES;
[CATransaction commit];

break;
default:
break;
}

_state = aState;
}

#pragma mark -
#pragma mark ScrollView Methods

//手指屏幕上不断拖动调用此方法
- (void)loadMoreScrollViewDidScroll:(UIScrollView *)scrollView {

if (_state == LoadMoreLoading) {

//CGFloat offset = MAX(scrollView.contentOffset.y * -1, 0);
//offset = MIN(offset, 60);
scrollView.contentInset = UIEdgeInsetsMake(0.0, 0.0f, LoadMoreViewHight, 0.0f);

} else if (scrollView.isDragging) {

BOOL _loading = NO;
if ([_delegate respondsToSelector:@selector( loadMoreTableFooterDataSourceIsLoading:)]) {
_loading = [_delegate loadMoreTableFooterDataSourceIsLoading:self];
}

if (_state == LoadMorePulling && scrollView.contentOffset.y + (scrollView.frame.size.height) < scrollView.contentSize.height + LoadMoreViewHight && scrollView.contentOffset.y > 0.0f && !_loading) {
[self setState:LoadMoreNormal];
} else if (_state == LoadMoreNormal && scrollView.contentOffset.y + (scrollView.frame.size.height) > scrollView.contentSize.height + LoadMoreViewHight && !_loading) {
[self setState:LoadMorePulling];
}

if (scrollView.contentInset.bottom != 0) {
scrollView.contentInset = UIEdgeInsetsZero;
}

}

}

//当用户停止拖动，并且手指从屏幕中拿开的的时候调用此方法
- (void)loadMoreshScrollViewDidEndDragging:(UIScrollView *)scrollView {

BOOL _loading = NO;
if ([_delegate respondsToSelector:@selector(loadMoreTableFooterDataSourceIsLoading:)]) {
_loading = [_delegate loadMoreTableFooterDataSourceIsLoading:self];
}

if (scrollView.contentOffset.y + (scrollView.frame.size.height) > scrollView.contentSize.height + LoadMoreViewHight && !_loading) {

if ([_delegate respondsToSelector:@selector(loadMoreTableFooterDidTriggerRefresh:)]) {
[_delegate loadMoreTableFooterDidTriggerRefresh:self];
}

[self setState:LoadMoreLoading];
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:0.2];
scrollView.contentInset = UIEdgeInsetsMake(0.0f, 0.0f, LoadMoreViewHight, 0.0f);
[UIView commitAnimations];

}

}

//当开发者页面页面刷新完毕调用此方法，[delegate egoRefreshScrollViewDataSourceDidFinishedLoading: scrollView];
- (void)loadMoreshScrollViewDataSourceDidFinishedLoading:(UIScrollView *)scrollView {

[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:.3];
[scrollView setContentInset:UIEdgeInsetsMake(0.0f, 0.0f, 0.0f, 0.0f)];
[UIView commitAnimations];

[self setState:LoadMoreNormal];

}
#pragma mark -
#pragma mark Dealloc

(void)dealloc {

_delegate=nil;
_activityView = nil;
_statusLabel = nil;
_arrowImage = nil;
//_lastUpdatedLabel = nil;
[super dealloc];
}

@end

怎么使用：
1.实现代理LoadMoreTableFooterViewDelegate
2.

 -(void)viewDidLoad{
...
if(self.tableView.tableFooterView == nil) {
[self loadMoreFooterInit];
}

}
-(void)loadMoreFooterInit{

if (_loadMoreTableFooterView == nil) {

LoadMoreTableFooterView *view = [[LoadMoreTableFooterView alloc] initWithFrame:CGRectMake(0, 0, 320, 44)];
view.delegate = self;
self.tableView.tableFooterView = view;
//[self.tableView addSubview:view];
_loadMoreTableFooterView = view;
[self.tableView.tableFooterView setHidden:YES];//self.tableView.tableFooterView 你的tableview
[view release];
//[_loadMoreTableFooterView setHidden:YES];

}

}