iphone开发中的一些小技巧

经过半年多的iphone开发，我发现在开发过程中最难的就是一些嘈杂的细节，而了解一些小技巧就会达到事半功倍的效果，下面我就总结一下在iphone开发中的一些小技巧。

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 = [UIImageimageNamed:filename];

CGImageRef imageRef = image.CGImage;

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

CGImageRef imageRefRect =CGImageCreateWithImageInRect(imageRef, rect);

UIImage *imageRect = [[UIImagealloc]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 = [NSPredicatepredicateWithFormat:@"SELF MATCHES %@", emailRegex];

return[emailTestevaluateWithObject: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.layerrenderInContext: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=[[UILocalNotificationalloc]init];

if(notification!=nil) {

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

NSDate*now=[NSDatenew];

notification.fireDate=[nowaddTimeInterval:10];

notification.timeZone=[NSTimeZonedefaultTimeZone];

notification.alertBody=@"该去吃晚饭了！";

[[UIApplicationsharedApplication].scheduleLocalNotification:notification];

}

6、捕获iphone通话事件：

CTCallCenter *center = [[CTCallCenteralloc]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：

floatrotateAngle =M_PI;

CGAffineTransform transform =CGAffineTransformMakeRotation(rotateAngle);

imageView.transform = transform;

9、设置旋转的原点：

#import<QuartzCore/QuartzCore.h>

UIImageView *imageView = [[UIImageViewalloc]initWithImage:[UIImageimageNamed:@"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 = [[UIWindowalloc]initWithFrame:frame];

[wdsetBackgroundColor:[UIColorclearColor]];

[wdsetWindowLevel:UIWindowLevelStatusBar];

frame =CGRectMake(100,0,30,20);

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

[imgsetContentMode:UIViewContentModeCenter];

[imgsetImage:[UIImageimageNamed:@"00_0103.png"]];

[wdaddSubview:img];

[wdmakeKeyAndVisible];

[UIViewbeginAnimations:nilcontext:nil];

[UIViewsetAnimationDuration:2];

frame.origin.x +=150;

[imgsetFrame:frame];

[UIViewcommitAnimations];

11、在程序中实现电话的拨打：

//添加电话图标按钮

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

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

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

[btnPhonesetBackgroundImage:imageforState:UIControlStateNormal];

//点击拨号按钮直接拨号

[btnPhoneaddTarget:selfaction:@selector(callAction:event:)forControlEvents:UIControlEventTouchUpInside];

[cell.contentViewaddSubview: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 = [eventallTouches];

UITouch*touch = [touchesanyObject];

CGPointcurrentTouchPosition = [touchlocationInView:self.listTable];

NSIndexPath*indexPath = [self.listTableindexPathForRowAtPoint: currentTouchPosition];

if(indexPath ==nil) {

return;

}

NSIntegersection = [indexPathsection];

NSUIntegerrow = [indexPathrow];

NSDictionary*rowData = [datasobjectAtIndex:row];

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

[[UIApplicationsharedApplication]openURL:[NSURLURLWithString: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 = [[UIApplicationsharedApplication]windows];

for(UIView*winws){

NSArray*vs = [wsubviews];

for(UIView*vinvs)

{

if([[NSStringstringWithUTF8String:object_getClassName(v)]isEqualToString:@"UIKeyboard"])

{

v.backgroundColor= [UIColorredColor];

}

}

}

13、设置时区

NSTimeZone*defaultTimeZone = [NSTimeZonedefaultTimeZone];

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

[NSTimeZonesetDefaultTimeZone: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。

[[NSNotificationCenterdefaultCenter]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

{

floatnumber =0.0;

intindex =0;

for(index; index < [textlength]; index++)

{

NSString*protoText = [textsubstringToIndex:[textlength] - index];

NSString*toChangetext = [textsubstringToIndex:[textlength] -1-index];

NSString*charater;

if([toChangetextlength]==0)

{

charater = protoText;

}

else

{

NSRangerange = [textrangeOfString:toChangetext];

charater = [protoTextstringByReplacingCharactersInRange:rangewithString:@""];

}

NSLog(charater);

if([charaterlengthOfBytesUsingEncoding:NSUTF8StringEncoding] ==3)

{

number++;

}

else

{

number = number+0.5;

}

}

returnceil(number);

}