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 = [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);
}
[self.downloadButton removeTarget:self action:NULL forControlEvents:UIControlEventTouchUpInside];
[self.downloadButton addTarget:self action:@selector(pauseDownload) forControlEvents:UIControlEventTouchUpInside];