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);?
}