iPhone开发小技巧

1、如果在程序中想对某张图片进行处理的话（得到某张图片的一部分）可一用以下代码： 

UIImage *image = [UIImage imageNamed:filename]; 

CGImageRef imageRef = image.CGImage; 

CGRect rect = CGRectMake(origin.x, origin.y ,size.width, size.height); 

CGImageRef imageRefRect = CGImageCreateWithImageInRect(imageRef, rect); 

UIImage *imageRect = [[UIImage alloc] initWithCGImage:imageRefRect]; 



2、判断设备是iphone还是iphone4的代码： 


#define isRetina ([UIScreen instancesRespondToSelector:@selector(currentMode)] ? CGSizeEqualToSize(CGSizeMake(640, 960), [[UIScreen mainScreen] currentMode].size) : NO) 


3、判断邮箱输入的是否正确： 


- (BOOL) validateEmail: (NSString *) candidate { 

NSString *emailRegex = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}"; 

NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex]; 



return [emailTest evaluateWithObject:candidate]; 

} 



4、如何把当前的视图作为照片保存到相册中去： 



#import <QuartzCore/QuartzCore.h> 

UIGraphicsBeginImageContext(currentView.bounds.size);     //currentView 当前的view 

[currentView.layer renderInContext:UIGraphicsGetCurrentContext()]; 

UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext(); 

UIGraphicsEndImageContext(); 

UIImageWriteToSavedPhotosAlbum(viewImage, nil, nil, nil); 



5、本地通知（类似于push通知）按home键到后台 十秒后触发： 

UILocalNotification *notification=[[UILocalNotification alloc] init]; 

if (notification!=nil) { 

NSLog(@">> support local notification"); 

NSDate *now=[NSDate new]; 

notification.fireDate=[now addTimeInterval:10]; 

notification.timeZone=[NSTimeZone defaultTimeZone]; 

notification.alertBody=@"该去吃晚饭了！"; 

[[UIApplication sharedApplication].scheduleLocalNotification:notification]; 

} 



6、捕获iphone通话事件： 

CTCallCenter *center = [[CTCallCenter alloc] init]; 

center.callEventHandler = ^(CTCall *call) 

{ 

NSLog(@"call:%@", call.callState); 

} 



7、iOS 4 引入了多任务支持，所以用户按下 “Home” 键以后程序可能并没有退出而是转入了后台运行。如果您想让应用直接退出，最简单的方法是：在 info－plist 里面找到 Application does not run in background 一项，勾选即可。 


8、使UIimageView的图像旋转： 


float rotateAngle = M_PI; 

CGAffineTransform transform =CGAffineTransformMakeRotation(rotateAngle); 

imageView.transform = transform; 



9、设置旋转的原点： 



#import <QuartzCore/QuartzCore.h> 

UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"bg.png"]]; 

imageView.layer.anchorPoint = CGPointMake(0.5, 1.0); 



10、实现自定义的状态栏（遮盖状态栏）： 

CGRect frame = {{0, 0}, {320, 20}}; 

UIWindow* wd = [[UIWindow alloc] initWithFrame:frame]; 

[wd setBackgroundColor:[UIColor clearColor]]; 

[wd setWindowLevel:UIWindowLevelStatusBar]; 

frame = CGRectMake(100, 0, 30, 20); 

UIImageView* img = [[UIImageView alloc] initWithFrame:frame]; 

[img setContentMode:UIViewContentModeCenter]; 

[img setImage:[UIImage imageNamed:@"00_0103.png"]]; 

[wd addSubview:img]; 

[wd makeKeyAndVisible]; 



[UIView beginAnimations:nil context:nil]; 

[UIView setAnimationDuration:2]; 

frame.origin.x += 150; 

[img setFrame:frame]; 

[UIView commitAnimations]; 


11、在程序中实现电话的拨打： 


//添加电话图标按钮 

UIButton *btnPhone = [[UIButton buttonWithType:UIButtonTypeCustom] retain]; 

btnPhone.frame = CGRectMake(280,10,30,30); 

UIImage *image = [UIImage imageNamed:@"phone.png"];     

[btnPhone setBackgroundImage:image forState:UIControlStateNormal]; 



//点击拨号按钮直接拨号 

[btnPhone addTarget:self action:@selector(callAction:event:)forControlEvents:UIControlEventTouchUpInside]; 



[cell.contentView addSubview:btnPhone];  //cell是一个UITableViewCell 



//定义点击拨号按钮时的操作 

- (void)callAction:(id)sender event:(id)event{ 

NSSet *touches = [event allTouches]; 

UITouch *touch = [touches anyObject]; 

CGPoint currentTouchPosition = [touch locationInView:self.listTable]; 

NSIndexPath *indexPath = [self.listTable indexPathForRowAtPoint: currentTouchPosition]; 

if (indexPath == nil) { 

return; 

} 

NSInteger section = [indexPath section]; 

NSUInteger row = [indexPath row]; 

NSDictionary *rowData = [datas objectAtIndex:row]; 



NSString *num = [[NSString alloc] initWithFormat:@"tel://%@",number]; //number为号码字符串     

[[UIApplication sharedApplication] openURL:[NSURL URLWithString:num]]; //拨号 

} 


12、更改iphone的键盘颜色： 


1.只有这2种数字键盘才有效果。UIKeyboardTypeNumberPad，UIKeyboardTypePhonePad 

2. keyboardAppearance ＝ UIKeyboardAppearanceAlert 

- (void)textViewDidBeginEditing:(UITextView *)textView{ 

NSArray *ws = [[UIApplication sharedApplication] windows]; 

for(UIView *w in ws){ 

NSArray *vs = [w subviews]; 

for(UIView *v in vs) 

{ 

if([[NSString stringWithUTF8String:object_getClassName(v)] isEqualToString:@"UIKeyboard"]) 

{ 

v.backgroundColor = [UIColor redColor]; 

} 

} 

} 



13、设置时区 




NSTimeZone *defaultTimeZone = [NSTimeZone defaultTimeZone]; 

NSTimeZone *tzGMT = [NSTimeZone timeZoneWithName:@"GMT"]; 

[NSTimeZone setDefaultTimeZone:tzGMT]; 

上面两个时区任意用一个。 


14、Ipad隐藏键盘的同时触发方法。 





[[NSNotificationCenter defaultCenter] addObserver:self 

selector:@selector(keyboardWillHide:) 

name:UIKeyboardWillHideNotification 

  object:nil]; 



- (IBAction)keyboardWillHide:(NSNotification *)note 



14、在一个程序中打开另一个程序的方法。 



http://www.cocoachina.com/iphonedev/sdk/2010/0322/768.html 

15、计算字符串的字数 

-(int)calculateTextNumber:(NSString *)text 

{ 

float number = 0.0; 

int index = 0; 

for (index; index < [text length]; index++) 

{ 

NSString *protoText = [text substringToIndex:[text length] - index]; 

NSString *toChangetext = [text substringToIndex:[text length] -1 -index]; 

NSString *charater; 

if ([toChangetext length]==0) 

{ 

charater = protoText; 

} 

else 

{ 

NSRange range = [text rangeOfString:toChangetext]; 

charater = [protoText stringByReplacingCharactersInRange:range withString:@""]; 



} 

NSLog(charater); 

if ([charater lengthOfBytesUsingEncoding:NSUTF8StringEncoding] == 3) 

{ 

number++; 

} 

else 

{ 

number = number+0.5; 

} 

} 

return ceil(number); 
}