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IOS 开发常用代码

阴影
UIView *feeView = [[UIView alloc] initWithFrame:CGRectMake(20, 20, 280, 200)];//计费显示

[https://www.wendangku.net/doc/384585437.html,yer setBorderWidth: 2.0];
[https://www.wendangku.net/doc/384585437.html,yer setCornerRadius:20.0f];
[https://www.wendangku.net/doc/384585437.html,yer setMasksToBounds:NO];
[https://www.wendangku.net/doc/384585437.html,yer setBorderColor: [[UIColor lightGrayColor] CGColor]];

UIColor * highColor = [UIColor colorWithWhite:1.000 alpha:1.000];
UIColor * lowColor = [UIColor colorWithRed:0.851 green:0.859 blue:0.867 alpha:1.000];

CAGradientLayer * gradient = [CAGradientLayer layer];
[gradient setFrame:[feeView bounds]];
[gradient setColors:[NSArray arrayWithObjects:(id)[highColor CGColor], (id)[lowColor CGColor], nil]];
//the rounded rect, with a corner radius of 6 points.
//this *does* maskToBounds so that any sublayers are masked
//this allows the gradient to appear to have rounded corners
// CALayer * roundRect = [CALayer layer];
// [roundRect setFrame:[feeView bounds]];
// [roundRect setCornerRadius:6.0f];
// [roundRect setMasksToBounds:YES];
// [roundRect addSublayer:gradient];
//
// [https://www.wendangku.net/doc/384585437.html,yer insertSublayer:roundRect atIndex:0];
//set the shadow on the view's layer
[https://www.wendangku.net/doc/384585437.html,yer setShadowColor:[[UIColor blackColor] CGColor]];
[https://www.wendangku.net/doc/384585437.html,yer setShadowOffset:CGSizeMake(0, 0)];
[https://www.wendangku.net/doc/384585437.html,yer setShadowOpacity:1.0];
[https://www.wendangku.net/doc/384585437.html,yer setShadowRadius:10.0];

[feeView setBackgroundColor:[UIColor whiteColor]];
为视图加边框
[[UIApplication sharedApplication] setStatusBarHidden:YES withAnimation: UIStatusBarAnimationSlide];
UIImageView *contentView = [[MyUIImageView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];
[contentView setImage:[UIImage imageNamed:@"1.jpg"]];
[contentView setUserInteractionEnabled:YES];

self.view=[[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];
[self.view addSubview:contentView];
self.view.backgroundColor=[UIColor blackColor];

/*
CALayer *layer=[contentView layer];
[layer setMasksToBounds:YES];
[layer setCornerRadius:10.0];
[layer setBorderWidth:4.0];
*/

//为视图增加边框
https://www.wendangku.net/doc/384585437.html,yer.masksToBounds=YES;
https://www.wendangku.net/doc/384585437.html,yer.cornerRadius=20.0;
https://www.wendangku.net/doc/384585437.html,yer.borderWidth=10.0;
https://www.wendangku.net/doc/384585437.html,yer.borderColor=[[UIColor blueColor] CGColor];
UIImage 图片缩放到指定大小尺寸
2011/03/26 17:43
lazytable 例子
// Set appIcon and clear temporary data/image
UIImage *image = [[UIImage alloc] initWithData:self.activeDownload];

if (image.size.width != kAppIconHeight && image.size.height != kAppIconHeight)
{
CGSize itemSize = CGSizeMake(kAppIconHeight, kAppIconHeight);
UIGraphicsBeginImageContext(itemSize);
CGRect imageRect = CGRectMake(0.0, 0.0, itemSize.width, itemSize.height);
[image drawInRect:imageRect];
self.appRecord.appIcon = UIGraphicsGetIma

geFromCurrentImageContext();
UIGraphicsEndImageContext();
}
else
{
self.appRecord.appIcon = image;
}

self.activeDownload = nil;
[image release];

图片缩放到指定大小尺寸
- (UIImage *)scaleToSize:(UIImage *)img size:(CGSize)size{
// 创建一个bitmap的context
// 并把它设置成为当前正在使用的context
UIGraphicsBeginImageContext(size);
// 绘制改变大小的图片
[img drawInRect:CGRectMake(0, 0, size.width, size.height)];
// 从当前context中创建一个改变大小后的图片
UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();
// 使当前的context出堆栈
UIGraphicsEndImageContext();
// 返回新的改变大小后的图片
return scaledImage;
}
判断设备
if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad) ｛
NSLog(@"ipad");
｝
else
{
NSLog(@"iphone or ipod");
}
判断分辨率
- (void)viewDidLoad
{
[super viewDidLoad];

// Do any additional setup after loading the view from its nib.
UIImage *logo = [UIImage imageNamed:@"icon@2x.png"];

UIScreenMode *sm =[[UIScreen mainScreen] currentMode];
CGSize cs = sm.size;

//可以判断出屏幕分辨率
MCLog(@"%f x %f", cs.width,cs.height);

// CGRect cr = [[UIScreen mainScreen] applicationFrame];
// MCLog(@"%f x %f", cr.size.width,cr.size.height);

CGSize frame = [logo size];
CGRect viewRect = CGRectMake(10, 10, frame.width, frame.height);
//UIView* myView = [[UIView alloc] initWithFrame:viewRect];
[logoImageView setFrame:viewRect];

[logoImageView setImage:logo];
}
iphone CGContextSetLineWidth 画线的问题
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBStrokeColor (context, 142.0/ 255.0, 161.0/ 255.0, 189.0/ 255.0, 1.0);
CGContextSetLineWidth(context, 1.0 );//这里设置成了1但画出的线还是2px,给我们的感觉好像最小只能是2px。
CGContextMoveToPoint(context, 1.0 , 24.0 );
CGContextAddLineToPoint(context, 83.0 , 24.0 );
CGContextClosePath(context);
CGContextStrokePath(context);

原因是因为默认情况下，锯齿显示，所以它显示为宽度= 2.0，关闭消除锯齿可以解决问题了。

CGContextSetShouldAntialias(context, NO );
获取上下文
CGContextRef context = UIGraphicsGetCurrentContext();

画一个正方形图形没有边框
CGContextSetRGBFillColor(context, 0, 0.25, 0, 0.5);
CGContextFillRect(context, CGRectMake(2, 2, 270, 270));
CGContextStrokePath(context);

写文字
CGContextSetLineWidth(context, 1.0);
CGContextSetRGBFillColor (context, 1, 1, 1, 1.0);
UIFont *font = [UIFont boldSystemFontOfSize:11.0];
[@"fangyp" drawInRect:CGRectMake(40, 40, 80, 20) withFont:font];

画一条线
CGContextSetRGBStrokeColor(context, 0.5, 0.5, 0.5, 0.5);//线条颜色
CGContextMoveToPoint(context, 20, 20);
CGContextAddLineToPoint(context, 200,20);
CGContextStroke

Path(context);

画正方形边框
CGContextSetRGBStrokeColor(context, 1, 1.0, 1.0, 1.0);
CGContextSetLineWidth(context, 2.0);
CGContextAddRect(context, CGRectMake(2, 2, 270, 270));
CGContextStrokePath(context);
2.等待线程运行结束后，再执行后面的代码。
-(IBAction)start:(id)sender
{
pageStillLoading=燳ES;
[NSThread燿etachNewThreadSelector:@selector(loadPageInBackground:)toTarget:self withObject:nil];
[progress setHidden:NO];
while(pageStillLoading)爗
[NSRunLoop燾urrentRunLoop]爎unMode:NSDefaultRunLoopMode beforeDate:[NSDate燿istantFuture]];
}
[progress setHidden:YES];
}
objective-c获取自1970年以来的毫秒数
NSTimeInterval time=[[NSDate date] timeIntervalSince1970]*1000;
double i=time; //NSTimeInterval返回的是double类型
NSLog(@"1970timeInterval:%f",i);
java获取自1970年以来的毫秒数
long startPaintLogoTime=System.currentTimeMillis();
- (float) os_time
{
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"MM-dd-hh-mm-ss-HHMM"];
NSString*locationString=[formatter stringFromDate: [NSDate date]];
NSArray*timeArray=[locationString componentsSeparatedByString:@"-"];
float value_D= [[timeArray objectAtIndex:1]floatValue];
float value_h= [ [timeArray objectAtIndex:2]floatValue];
float value_m= [ [timeArray objectAtIndex:3]floatValue];
float value_s= [ [timeArray objectAtIndex:4]floatValue];
//时区偏移量。
float value_f= [ [timeArray objectAtIndex:5]floatValue];
float value_All=value_D*24*60*60+value_h*60*60+value_m*60+value_s;
[formatter release];
return value_All;
}
保存图片
(void)saveImageToPhone
{

UIImageWriteToSavedPhotosAlbum(img,nil, nil, nil);

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil
message:@"您已将照片存储于图片库中，打开照片程序即可查看。"
delegate:self
cancelButtonTitle:@"OK"
otherButtonTitles:nil];

[alert show];
[alert release];

}
#import
-(void)saveCurrentScreenToPhone
{

UIGraphicsBeginImageContext(self.view.bounds.size);
[https://www.wendangku.net/doc/384585437.html,yer renderInContext:UIGraphicsGetCurrentContext()];
UIImage*viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(viewImage,nil, nil, nil);

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil
message:@"您已将当前屏幕截图存储在图片库中，打开照片程序即可查看。"
delegate:self
cancelButtonTitle:@"OK"
otherButtonTitles:nil];

[a

lert show];
[alert release];
}
添加一个按钮
//create a Button view
//创建一个按钮，这个按钮接收事件slideShow
CGRect frame=CGRectMake(10,70,300,50);
UIButton *button=[UIButton buttonWithType:UIButtonTypeRoundedRect];
button.frame=frame;
[button setTitle:@"Click Me,please!" forState:UIControlStateNormal];
button.backgroundColor=[UIColor clearColor];
button.tag=2000;
[button addTarget:self action:@selector(slideShow:)
forControlEvents:UIControlEventTouchUpInside];
[window addSubview:button];

[self.window makeKeyAndVisible];
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Iphone 开发常用代码
#pragma mark -
#pragma mark 重写父类方法，UIResponder中方法。
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{
NSUInteger touchCount = [touches count];
if (touchCount == 1)
{
UITouch* touch = [[touches allObjects] objectAtIndex:0];
CGPoint touchPoint = [touch locationInView: self.view];
}
}
取鼠标点击屏幕区域的坐标。
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
NSUInteger touchCount = [touches count];
if (touchCount == 1)
{
UITouch* touch = [[touches allObjects] objectAtIndex:0];
CGPoint touchPoint = [touch locationInView: self.view];
}
}
1、在地图中添加一个手势，这个手势是一个点击动作，点击时会调用tapPress这个方法
UITapGestureRecognizer *mTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapPress:)];
[myMapView addGestureRecognizer:mTap];
[mTap release];
2、接下来就可以在tapPress这个方法中进行转换了
- (void)tapPress:(UIGestureRecognizer*)gestureRecognizer {

CGPoint touchPoint = [gestureRecognizer locationInView:myMapView];//这里touchPoint是点击的某点在地图控件中的位置
CLLocationCoordinate2D touchMapCoordinate =
[myMapView convertPoint:touchPoint toCoordinateFromView:myMapView];//这里touchMapCoordinate就是该点的经纬度了
}
//坐标转换
CGPoint touchPoint = [gestureRecognizer locationInView:m_mapView];
CLLocationCoordinate2D touchMapCoordinate =
[m_mapView convertPoint:touchPoint toCoordinateFromView:m_mapView];
//annotationView图片。
// annotationView.image = [UIImage imageNamed:@"history.png"];
//根据随机函数，生成annotation.
// NSMutableArray *marray = [NSMutableArray arrayWithCapacity:50];
// for (int i =0; i<=50; i++ ) {
// float lat = [CommonUtils randomValueBetween:37.0 andValue:37.35];
// float longi = [CommonUtils randomValueBetween:-122.3 andValue:-121.5];
// CLLocationCoordinate2D tmpcoordinate = {lat, longi};
// MCUserAnnotation* markera = [[MCUserAnnotation alloc] initWithCoordinate:tmpcoordinate];
// markera._name = @"vvv";
//

// //[mapView addAnnotation:marker];
// // [mapView addAnnotation:markera];
// [marray insertObject:markera atIndex:i];
// [markera release];
//
//
// }
// [mapView addAnnotations:marray];
添加一个按钮在nav bar上面。
// UIBarButtonItem *cancelButton = [[UIBarButtonItem alloc]
// initWithTitle:@"Cancel"
// style:UIBarButtonItemStylePlain
// target:self
// action:@selector(cancel:)];
// self.navBar.leftBarButtonItem = cancelButton;
// [cancelButton release];
获取坐标；
// CLLocationCoordinate2D coordinate = [[mapView userLocation] coordinate];
// CLLocationCoordinate2D mapCenter = mapView.centerCoordinate;
将点转换为坐标。经纬度
// mapCenter = [mapView convertPoint:
// CGPointMake(1, (mapView.frame.size.height/2.0))
// toCoordinateFromView:mapView];
使用MKMapView时，点击iPhone屏幕，大头针落在触点的代码
- (MKAnnotationView *)mapView:(MKMapView *)mV viewForAnnotation:(id )annotation
{
MKPinAnnotationView *pinView = nil;
if(annotation != https://www.wendangku.net/doc/384585437.html,erLocation)
{
static NSString *defaultPinID = @”目的地”;
pinView = (MKPinAnnotationView *)[mapView dequeueReusableAnnotationViewWithIdentifier:defaultPinID];
if ( pinView == nil )
pinView = [[[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:defaultPinID] autorelease];
pinView.pinColor = MKPinAnnotationColorPurple;
pinView.canShowCallout = YES;
pinView.animatesDrop = YES;
pinView.draggable=YES;
pinView.selected=YES;
}
else
{
[https://www.wendangku.net/doc/384585437.html,erLocation setTitle:@"I am here"];
}
return pinView;
}
segmentContro选择地图。
-(IBAction)switchControl:(id)sender{
switch (((UISegmentedControl *)sender).selectedSegmentIndex) { case 0: { mapView.mapType = MKMapTypeStandard; break; } case 1: { mapView.mapType = MKMapTypeSatellite; break; } default: { mapView.mapType = MKMapTypeHybrid; break; } }
}

自定义按钮
prevButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"上一项" style:UIBarButtonItemStyleBordered target:self action:@selector(ShowPrevious)];
view = [[UIToolbar alloc] initWithFrame:CGRectMake(0,480,320,44)];
view.barStyle = UIBarStyleBlackTranslucent;
view.items = [NSArray arrayWithObjects:prevButtonItem,nextButtonItem,spaceButtonItem,hiddenButtonItem,nil];

更改cell选中的背景
UIView *myview = [[UIView alloc] init];
myview.frame = CGRectMake(0, 0, 320, 47);
myview.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"0006.png"]];
cell.selectedBackgroundView = myview;

在数字键盘上添加button：
//定义一个消息中心
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selecto

r(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil]; //addObserver:注册一个观察员 name:消息名称
- (void)keyboardWillShow:(NSNotification *)note {
// create custom button
UIButton *doneButton = [UIButton buttonWithType:UIButtonTypeCustom];
doneButton.frame = CGRectMake(0, 163, 106, 53);
[doneButton setImage:[UIImage imageNamed:@"5.png"] forState:UIControlStateNormal];
[doneButton addTarget:self action:@selector(addRadixPoint) forControlEvents:UIControlEventTouchUpInside];

// locate keyboard view
UIWindow* tempWindow = [[[UIApplication sharedApplication] windows] objectAtIndex:1];//返回应用程序window
UIView* keyboard;
for(int i=0; i<[tempWindow.subviews count]; i++) //遍历window上的所有subview
{
keyboard = [tempWindow.subviews objectAtIndex:i];
// keyboard view found; add the custom button to it
if([[keyboard description] hasPrefix:@"[keyboard addSubview:doneButton];
}
}

正则表达式使用：
被用于正则表达式的字串必须是可变长的，不然会出问题

将一个空间放在视图之上
[scrollView insertSubview:searchButton aboveSubview:scrollView];

从本地加载图片
NSString *boundle = [[NSBundle mainBundle] resourcePath];
[web1 loadHTMLString:[NSString stringWithFormat:@""] baseURL:[NSURL fileURLWithPath:boundle]];

从网页加载图片并让图片在规定长宽中缩小
[cell.img loadHTMLString:[NSString stringWithFormat:@"",goodsInfo.GoodsImg] baseURL:nil];
将网页加载到webview上通过javascript获取里面的数据，如果只是发送了一个连接请求获取到源码以后可以用正则表达式进行获取数据
NSString *javaScript1 = @"document.getElementsByName('.u').item(0).value";
NSString *javaScript2 = @"document.getElementsByName('.challenge').item(0).value";
NSString *strResult1 = [NSString stringWithString:[theWebView stringByEvaluatingJavaScriptFromString:javaScript1]];
NSString *strResult2 = [NSString stringWithString:[theWebView stringByEvaluatingJavaScriptFromString:javaScript2]];

用NSString怎么把UTF8转换成unicode
utf8Str //
NSString *unicodeStr = [NSString stringWithCString:[utf8Str UTF8String] encoding:NSUnicodeStringEncoding];

View自己调用自己的方法:
[self performSelector:@selector(loginToNext) withObject:nil afterDelay:2];//黄色段为方法名,和延迟几秒执行.

显示图像:
CGRect myImageRect = CGRectMake(0.0f, 0.0f, 320.0f, 109.0f);
UIImageView *myImage = [[UIImageView alloc] initWithFrame:myImageRect];
[myImage setImage:[UIImage imageNamed:@"myImage.png"]];
myImage.opaque = YES; //opaque是否透明
[self.view addSubview:myImage];
[myImage release];

WebView:
CGRect webFrame = CGRectMake(0.0, 0.0, 320.0, 460.0);
UIWebView *webView = [[UIWebView alloc] initWithFrame:webFrame];
[w

ebView setBackgroundColor:[UIColor whiteColor]];
NSString *urlAddress = @"https://www.wendangku.net/doc/384585437.html,";
NSURL *url = [NSURL URLWithString:urlAddress];
NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];
[webView loadRequest:requestObj];
[self addSubview:webView];
[webView release];

显示网络活动状态指示符
这是在iPhone左上部的状态栏显示的转动的图标指示有背景发生网络的活动。
UIApplication* app = [UIApplication sharedApplication];
https://www.wendangku.net/doc/384585437.html,workActivityIndicatorVisible = YES;

动画:一个接一个地显示一系列的图象
NSArray *myImages = [NSArray arrayWithObjects: [UIImage imageNamed:@"myImage1.png"], [UIImage imageNamed:@"myImage2.png"], [UIImage imageNamed:@"myImage3.png"], [UIImage imageNamed:@"myImage4.gif"], nil];
UIImageView *myAnimatedView = [UIImageView alloc];
[myAnimatedView initWithFrame:[self bounds]];
myAnimatedView.animationImages = myImages; //animationImages属性返回一个存放动画图片的数组
myAnimatedView.animationDuration = 0.25; //浏览整个图片一次所用的时间
myAnimatedView.animationRepeatCount = 0; // 0 = loops forever 动画重复次数
[myAnimatedView startAnimating];
[self addSubview:myAnimatedView];
[myAnimatedView release];

动画:显示了something在屏幕上移动。注：这种类型的动画是“开始后不处理” -你不能获取任何有关物体在动画中的信息(如当前的位置) 。如果您需要此信息，您会手动使用定时器去调整动画的X和Y坐标
这个需要导入QuartzCore.framework
CABasicAnimation *theAnimation;
theAnimation=[CABasicAnimation animationWithKeyPath:@"transform.translation.x"];
//Creates and returns an CAPropertyAnimation instance for the specified key path.
//parameter:the key path of the property to be animated
theAnimation.duration=1;
theAnimation.repeatCount=2;
theAnimation.autoreverses=YES;
theAnimation.fromValue=[NSNumber numberWithFloat:0];
theAnimation.toValue=[NSNumber numberWithFloat:-60];
[https://www.wendangku.net/doc/384585437.html,yer addAnimation:theAnimation forKey:@"animateLayer"];

Draggable items//拖动项目
Here's how to create a simple draggable image.//这是如何生成一个简单的拖动图象
1. Create a new class that inherits from UIImageView
@interface myDraggableImage : UIImageView { }
2. In the implementation for this new class, add the 2 methods:
- (void) touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event
{
// Retrieve the touch point 检索接触点
CGPoint pt = [[touches anyObject] locationInView:self];
startLocation = pt;
[[self superview] bringSubviewToFront:self];
}
- (void) touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event
{
// Move relative to the original touch point 相对以前的触摸点进行移动
CGPoint pt = [[touches anyObject] locationInView:self];
CGRect frame = [self frame];
frame.origin.x += pt.x - startLocation.x;
frame.origin.y += pt.y - startLocation.y;
[self setFrame:frame];
}
3. Now instantiate the new class a

s you would any other new image and add it to your view
//实例这个新的类,放到你需要新的图片放到你的视图上
dragger = [[myDraggableImage alloc] initWithFrame:myDragRect];
[dragger setImage:[UIImage imageNamed:@"myImage.png"]];
[dragger setUserInteractionEnabled:YES];

线程:
1. Create the new thread:
[NSThread detachNewThreadSelector:@selector(myMethod) toTarget:self withObject:nil];
2. Create the method that is called by the new thread:
- (void)myMethod
{
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
*** code that should be run in the new thread goes here ***
[pool release];
}
//What if you need to do something to the main thread from inside your new thread (for example, show a loading //symbol)? Use performSelectorOnMainThread.
[self performSelectorOnMainThread:@selector(myMethod) withObject:nil waitUntilDone:false];

Plist files
Application-specific plist files can be stored in the Resources folder of the app bundle. When the app first launches, it should check if there is an existing plist in the user's Documents folder, and if not it should copy the plist from the app bundle.
// Look in Documents for an existing plist file
NSArray *paths = NSSearchPathForDirectoriesInDomains( NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
myPlistPath = [documentsDirectory stringByAppendingPathComponent:
[NSString stringWithFormat: @"%@.plist", plistName] ];
[myPlistPath retain];
// If it's not there, copy it from the bundle
NSFileManager *fileManger = [NSFileManager defaultManager];
if ( ![fileManger fileExistsAtPath:myPlistPath] )
{
NSString *pathToSettingsInBundle = [[NSBundle mainBundle] pathForResource:plistName ofType:@"plist"];
}
//Now read the plist file from Documents
NSArray *paths = NSSearchPathForDirectoriesInDomains( NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectoryPath = [paths objectAtIndex:0];
NSString *path = [documentsDirectoryPath stringByAppendingPathComponent:@"myApp.plist"];
NSMutableDictionary *plist = [NSDictionary dictionaryWithContentsOfFile: path];
//Now read and set key/values
myKey = (int)[[plist valueForKey:@"myKey"] intValue];
myKey2 = (bool)[[plist valueForKey:@"myKey2"] boolValue];
[plist setValue:myKey forKey:@"myKey"];
[plist writeToFile:path atomically:YES];

Alerts
Show a simple alert with OK button.
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil message:
@"An Alert!" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
[alert show];
[alert release];

Info button
Increase the touchable area on the Info button, so it's easier to press.
CGRect newInfoButtonRect = CGRectMake(infoButton.frame.origin.x-25, infoButton.frame.origin.y-25, infoButton.frame.size.width+50, infoButton.frame.size.height+50);
[infoButton setFrame:newInfoButtonRect];

Detecting Subviews//子视图
You can loop through subviews of an existing view. This works especi

ally well if you use the "tag" property on your views.
for (UIImageView *anImage in [self.view subviews])
{
if (anImage.tag == 1)
{ // do something }
}