objective-c学习笔记

xcode cheetsheet

#@interface中声明变量是否是必须的

@interface Car : NSObject { 
	float p1; //可以删除
	float _p2;//可以删除
}
@property float p1; 
@property float p2;

@end


@implementation Car

@synthesize p1;
@synthesize p2 = _p2;

@end


# 解析sina微薄的created_at时间格式

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
	[formatter setDateFormat:@"EEE MMM dd HH:mm:ss ZZ yyyy"];  
	[formatter setLocale:[[NSLocale alloc] initWithLocaleIdentifier:@"en_US"]];
	
	NSLog(@"newDateString %@", [formatter dateFromString:@"Thu Sep 23 00:13:17 +0800 2010"]);

#option + click keyword
=> jump to document

#option+command + click keyword
=> find text in document



== 如何实现pull down to request
@interface PullToRefreshTableViewController : UITableViewController {
	EGORefreshTableHeaderView *refreshHeaderView;
}

@implementation PullToRefreshTableViewController
//用户开始下拉
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
        if (!reloading) {
		checkForRefresh = YES;  //  only check offset when dragging
		//更新视图中的"更新时间"
		refreshHeaderView.lastUpdatedDate = refreshHeaderView.lastUpdatedDate;
	}
} 

//用户下拉中...
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {	
	if (reloading) return;
	if (checkForRefresh) {
		if (refreshHeaderView.isFlipped && scrollView.contentOffset.y > -65.0f && scrollView.contentOffset.y < 0.0f && !reloading) {
               // 提示文字: 请下拉更新
			[refreshHeaderView flipImageAnimated:YES];
			[refreshHeaderView setStatus:kPullToReloadStatus];
		} else if (!refreshHeaderView.isFlipped && scrollView.contentOffset.y < -65.0f) {
               // 提示文字: 请松开,发出下拉请求
			[refreshHeaderView flipImageAnimated:YES];
			[refreshHeaderView setStatus:kReleaseToReloadStatus];
		}
	}
}

//用户终止下拉

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
	if (reloading) return;
        // 如果下拉距离大于65像素(13%), 显示pulling view...
	if (scrollView.contentOffset.y <= - 65.0f) {
		if ([self.tableView.dataSource respondsToSelector:@selector(reloadTableViewDataSource)]) {
			[self showReloadAnimationAnimated:YES];
			[self reloadTableViewDataSource];
		}
	}
        
        //不再检测下拉刷新 
	checkForRefresh = NO;
}



== how to use iphone preference

* create setting bundle, and add a item

<plist version="1.0">
<dict>
	<key>Title</key>
	<string>${PRODUCT_NAME}</string>
	<key>StringsTable</key>
	<string>Root</string>
	<key>PreferenceSpecifiers</key>
	<array>
		<dict>
			<key>Type</key>
			<string>PSGroupSpecifier</string>
			<key>Title</key>
			<string>Authentication</string>
		</dict>
		<dict>
					<key>Key</key>
					<string>delay</string>
					<key>DefaultValue</key>
					<string>2</string>
					<key>Title</key>
					<string>Delay</string>
					<key>Type</key>
					<string>PSTextFieldSpecifier</string>
				</dict>
				

* use in your code

NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSLog(@"..............................%@", [defaults valueForKey: @"delay"]);