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 = [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

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 

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);

}