iPhone开发中一些使用小技巧

经过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：
1. UIImage *image = [UIImage imageNamed:filename];
2. CGImageRef imageimageRef = image.CGImage;
3.
4. CGRect rect = CGRectMake(origin.x, origin.y ,size.width, size.height);
5.
6. CGImageRef imageRefRect = CGImageCreateWithImageInRect(imageRef, rect);
7.
8. UIImage *imageRect = [[UIImage alloc] initWithCGImage:imageRefRect];
2、判断设备是iphone还是iphone4的代码：
1. #define isRetina ([UIScreen instancesRespondToSelector:
2. @selector(currentMode)] ? CGSizeEqualToSize(CGSizeMake(640, 960),
3. [[UIScreen mainScreen] currentMode].size) : NO)
3、判断邮箱输入的是否正确：
1. - (BOOL) validateEmail: (NSString *) candidate {
2. NSString *emailRegex = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,4}";
3. NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];
4. return [emailTest evaluateWithObject:candidate];
5. }
4、如何把当前的视图作为照片保存到相册中去：
1. #import <QuartzCore/QuartzCore.h>
2. UIGraphicsBeginImageContext(currentView.bounds.size); //currentView 当前的view
3. [currentView.layer renderInContext:UIGraphicsGetCurrentContext()];
4. UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
5. UIGraphicsEndImageContext();
6. 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：
1. UILocalNotification *notification=[[UILocalNotification alloc] init];
2. if (notification!=nil) {
3. NSLog(@">> support local notification");
4. NSDate *now=[NSDate new];
5. notification.fireDate=[now addTimeInterval:10];
6. notification.timeZone=[NSTimeZone defaultTimeZone];
7. notification.alertBody=@"该去吃晚饭了！";
8. [[UIApplication sharedApplication].scheduleLocalNotification:notification];
9. }
6、捕获iphone通话事件：
1. CTCallCenter *center = [[CTCallCenter alloc] init];
2. center.callEventHandler = ^(CTCall *call)
3. {
4. NSLog(@"call:%@", call.callState);
5. }
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：
1. float rotateAngle = M_PI;
2. CGAffineTransform transform =CGAffineTransformMakeRotation(rotateAngle);
3. imageView.transform = transform;
9、设置旋转的原点：
1. #import <QuartzCore/QuartzCore.h>
2. UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"bg.png"]];
3. imageView.layer.anchorPoint = CGPointMake(0.5, 1.0);
10、实现自定义的状态栏（遮盖状态栏）：
1. CGRect frame = {{0, 0}, {320, 20}};
2. UIWindow* wd = [[UIWindow alloc] initWithFrame:frame];
3. [wd setBackgroundColor:[UIColor clearColor]];
4. [wd setWindowLevel:UIWindowLevelStatusBar];
5. frame = CGRectMake(100, 0, 30, 20);
6. UIImageView* img = [[UIImageView alloc] initWithFrame:frame];
7. [img setContentMode:UIViewContentModeCenter];
8. [img setImage:[UIImage imageNamed:@"00_0103.png"]];
9. [wd addSubview:img];
10.[wd makeKeyAndVisible];
11.[UIView beginAnimations:nil context:nil];
12.[UIView setAnimationDuration:2];
13.frame.origin.x += 150;
14.[img setFrame:frame];
15.[UIView commitAnimations];
11、在程序中实现电话的拨打：
1. //添加电话图标按钮
2. UIButton *btnPhone = [[UIButton buttonWithType:UIButtonTypeCustom] retain];
3. btnPhone.frame = CGRectMake(280,10,30,30);
4. UIImage *image = [UIImage imageNamed:@"phone.png"];
5. [btnPhone setBackgroundImage:image forState:UIControlStateNormal];
6. //点击拨号按钮直接拨号
7. [btnPhone addTarget:self action:@selector(callAction:event:) forControlEvents:UIControlEventTouchUpInside];
8. [cell.contentView addSubview:btnPhone]; //cell是一个UITableViewCell
9. //定义点击拨号按钮时的操作
10.- (void)callAction:(id)sender event:(id)event{
11.NSSet *touches = [event allTouches];
12.UITouch *touch = [touches anyObject];
13.CGPoint currentTouchPosition = [touch locationInView:self.listTable];
14.NSIndexPath *indexPath = [self.listTable indexPathForRowAtPoint: currentTouchPosition];
15.if (indexPath == nil) {
16.return;
17.}
18.NSInteger section = [indexPath section];
19.NSUInteger row = [indexPath row];
20.NSDictionary *rowData = [datas objectAtIndex:row];
21.NSString *num = [[NSString alloc] initWithFormat:@"tel://%@",number]; //number为号码字符串
22.[[UIApplication sharedApplication] openURL:[NSURL URLWithString:num]]; //拨号
23.}
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
1. - (void)textViewDidBeginEditing:(UITextView *)textView{
2. NSArray *ws = [[UIApplication sharedApplication] windows];
3. for(UIView *w in ws){
4. NSArray *vs = [w subviews];
5. for(UIView *v in vs)
6. {
7. if([[NSString stringWithUTF8String:object_getClassName(v)] isEqualToString:@"UIKeyboard"])
8. {
9. v.backgroundColor = [UIColor redColor];
10.}
11.}
12.}
13、设置时区
1. NSTimeZone *defaultTimeZone = [NSTimeZone defaultTimeZone];
2. NSTimeZone *tzGMT = [NSTimeZone timeZoneWithName:@"GMT"];
3. [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。
1. [[NSNotificationCenter defaultCenter] addObserver:self
2. selector:@selector(keyboardWillHide:)
3. name:UIKeyboardWillHideNotification
4. object:nil];
5. - (IBAction)keyboardWillHide:(NSNotification *)note
15、计算字符串的字数
1. -(int)calculateTextNumber:(NSString *)text
2. {
3. float number = 0.0;
4. int index = 0;
5. for (index; index < [text length]; index++)
6. {
7. NSString *protoText = [text substringToIndex:[text length] - index];
8. NSString *toChangetext = [text substringToIndex:[text length] -1 -index];
9. NSString *charater;
10.if ([toChangetext length]==0)
11.{
12.charater = protoText;
13.}
14.else
15.{
16.NSRange range = [text rangeOfString:toChangetext];
17.charater = [protoText stringByReplacingCharactersInRange:range withString:@""];
18.}
19.NSLog(charater);
20.if ([charater lengthOfBytesUsingEncoding:NSUTF8StringEncoding] == 3)
21.{
22.number++;
23.}
24.else
25.{
26.numbernumber = number+0.5;
27.}
28.}
29.return ceil(number);
30.}