iphone开发中一些常用的内容

UIEdgeInsets 设置包围tableView的坐标

typedef struct UIEdgeInsets {
    CGFloat top, left, bottom, right;  // specify amount to inset (positive) for each of the edges. values can be negative to 'outset'
} UIEdgeInsets;

里面分别是上，左，下，右的包围长度，往下拖动时，如果top 》 ０，　就会显示出来，如果小于０就会隐藏。

计算字符串的显示长度

CGSize detailSize = [@"你的字符串" sizeWithFont:[UIFont systemFontOfSize:15]
 constrainedToSize:CGSizeMake(200, MAXFLOAT) lineBreakMode:UILineBreakModeWordWrap];

navigationbar的back键触发其他事件

UIButton *back =[[UIButton alloc] initWithFrame:CGRectMake(200, 25, 63, 30)];
[back addTarget:self act
ion:@selector(reloadRowData:) forControlEvents:UIControlEventTouchUpInside];
[back setImage:[UIImage imageNamed:@"返回按钮.png"] forState:UIControlStateNormal];
UIBarButtonItem *backButtonItem = [[UIBarButtonItem alloc] initWithCustomView:back];
self.navigationItem.leftBarButtonItem = loginButtonItem
[back release];
[backButtonItem release];

防止屏幕暗掉锁屏

[[UIApplication sharedApplication] setIdleTimerDisabled:YES];

显示网络活动状态指示符

这是在iPhone左上部的状态栏显示的转动的图标指示有背景发生网络的活动。

UIApplication* app = [UIApplication sharedApplication];
app.networkActivityIndicatorVisible = YES;

获取UUID

[[UIDevice currentDevice] uniqueIdentifier]

UIDevice *myDevice = [UIDevice currentDevice];
NSString *deviceID = [myDevice uniqueIdentifier];

截取屏幕图片

UIGraphicsBeginImageContext(CGSizeMake(200,400));  //创建一个基于位图的图形上下文并指定大小为CGSizeMake(200,400)
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];  //renderInContext 呈现接受者及其子范围到指定的上下文
 UIImage *aImage = UIGraphicsGetImageFromCurrentImageContext(); //返回一个基于当前图形上下文的图片
UIGraphicsEndImageContext();   //移除栈顶的基于当前位图的图形上下文
imageData = UIImagePNGRepresentation(aImage); //以png格式返回指定图片的数据

应用程序边框大小

我们应该使用"bounds"来获得应用程序边框。不是用"applicationFrame"。"applicationFrame"还包含了一个20像素的status bar。除非我们需要那额外的20像素的status bar。

震动和声音播放

Sound will work in the Simulator, however some sound (such as looped) has been
 reported as not working in Simulator or even altogether depending on the audio format.
  Note there are specific filetypes that must be used (.wav in this example).

AudioServicesPlaySystemSound(kSystemSoundID_Vibrate);
SystemSoundID pmph;
id sndpath = ［NSBundle mainBundle] pathForResource:@"mySound"   ofType:@"wav"  inDirectory:@"/"];
CFURLRef baseURL = (CFURLRef) ［NSURL alloc] initFileURLWithPath:sndpath];
AudioServicesCreateSystemSoundID (baseURL, &pmph);
AudioServicesPlaySystemSound(pmph);
[baseURL release];

Iphone获取本机IP

-(NSString *)getAddress {
    char iphone_ip[255];
    strcpy(iphone_ip,"127.0.0.1"); // if everything fails
    NSHost* myhost =[NSHost currentHost];
    if (myhost)
    {
        NSString *ad = [myhost address];
        if (ad)
            strcpy(iphone_ip,[ad cStringUsingEncoding:NSASCIIStringEncoding]);
    }
    return [NSString stringWithFormat:@"%s",iphone_ip];
}

NSString转化为UNICODE String：

(NSString*)fname ＝ @“Test”;
char fnameStr[10];
memcpy(fnameStr, [fname cStringUsingEncoding:NSUnicodeStringEncoding], 2*([fname length]));

NSString转化为char

(NSString*)fname ＝ @“Test”;
char fnameStr[10];
fnameStr =[fname UTF8String];

char -> NSData:

   char * postData = "TEST";
   NSData *data = [NSData dataWithBytes:postData length:strlen(postData)];
    转换为NSString： - (id)initWithUTF8String:(const char *)bytes
    然后用NSString的 - (NSData *)dataUsingEncoding:(NSStringEncoding)encoding

NSData ->char

  NSData returnData;
  char* bu=[returnData bytes];

NSData->NSString

 NSString* aStr;
 aStr = ［NSString alloc] initWithData:aData encoding:NSASCIIStringEncoding];

NSString->NSData

 NSData* aData;
 aData = [aStr dataUsingEncoding: NSASCIIStringEncoding];