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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，UIKeyboardTypePhonePad2. 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:selfselector:@selector(keyboardWillHide:)name:UIKeyboardWillHideNotification object:nil];- (IBAction)keyboardWillHide:(NSNotification *)note14、在一个程序中打开另一个程序的方法。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);}