iPhone 开发过程中的一些小技术的总结（转）

1 随机数的使用

头文件的引用
#import <time.h>
#import <mach/mach_time.h>

srandom()的使用
srandom((unsigned)(mach_absolute_time() & 0xFFFFFFFF));

直接使用 random() 来调用随机数

2 在UIImageView 中旋转图像

float rotateAngle = M_PI;
CGAffineTransform transform =CGAffineTransformMakeRotation(rotateAngle);
imageView.transform = transform;

以上代码旋转imageView, 角度为rotateAngle, 方向可以自己测试哦！

3 在Quartz中如何设置旋转点

UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"bg.png"]];
imageView.layer.anchorPoint = CGPointMake(0.5, 1.0);

这个是把旋转点设置为底部中间。记住是在QuartzCore.framework中才得到支持。

4 创建.plist文件并存储

NSString *errorDesc; //用来存放错误信息
NSMutableDictionary *rootObj = [NSMutableDictionary dictionaryWithCapacity:4]; //NSDictionary, NSData等文件可以直接转化为plist文件
NSDictionary *innerDict;
NSString *name;
Player *player;
NSInteger saveIndex;

for(int i = 0; i < [playerArray count]; i++) {
player = nil;
player = [playerArray objectAtIndex:i];
if(player == nil)
break;
name = player.playerName;// This "Player1" denotes the player name could also be the computer name
innerDict = [self getAllNodeInfoToDictionary:player];
[rootObj setObject:innerDict forKey:name]; // This "Player1" denotes the person who start this game
}
player = nil;
NSData *plistData = [NSPropertyListSerialization dataFromPropertyList:(id)rootObj format:NSPropertyListXMLFormat_v1_0 errorDescription:&errorDesc];

红色部分可以忽略，只是给rootObj添加一点内容。这个plistData为创建好的plist文件，用其writeToFile方法就可以写成文件。下面是代码：

/*得到移动设备上的文件存放位置*/
NSString *documentsPath = [self getDocumentsDirectory];
NSString *savePath = [documentsPath stringByAppendingPathComponent:@"save.plist"];

/*存文件*/
if (plistData) {
[plistData writeToFile:savePath atomically:YES];
}
else {
NSLog(errorDesc);
[errorDesc release];
}

- (NSString *)getDocumentsDirectory {
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
return [paths objectAtIndex:0];
}

4 读取plist文件并转化为NSDictionary

NSString *documentsPath = [self getDocumentsDirectory];
NSString *fullPath = [documentsPath stringByAppendingPathComponent:@"save.plist"];
NSMutableDictionary* plistDict = [[NSMutableDictionary alloc] initWithContentsOfFile:fullPath];

5 读取一般性文档文件

NSString *tmp;
NSArray *lines; /*将文件转化为一行一行的*/
lines = [[NSString stringWithContentsOfFile:@"testFileReadLines.txt"]
componentsSeparatedByString:@"\n"];

NSEnumerator *nse = [lines objectEnumerator];

// 读取<>里的内容
while(tmp = [nse nextObject]) {
NSString *stringBetweenBrackets = nil;
NSScanner *scanner = [NSScanner scannerWithString:tmp];
[scanner scanUpToString:@"<" intoString:nil];
[scanner scanString:@"<" intoString:nil];
[scanner scanUpToString:@">" intoString:&stringBetweenBrackets];

NSLog([stringBetweenBrackets description]);
}

对于读写文件，还有补充，暂时到此。随机数和文件读写在游戏开发中经常用到。所以把部分内容放在这，以便和大家分享，也当记录，便于查找。

6 隐藏NavigationBar
[self.navigationController setNavigationBarHidden:YES animated:YES];

在想隐藏的ViewController中使用就可以了。
7 隐藏iAd

相信很多苹果开发者希望在自己的应用里加入 iAd 广告以提高收入，但是 iAd 广告显示目前仅限美国，所以取不到广告时，要让广告条隐藏，可以使用以下代码

- (void)bannerView:(ADBannerView *)banner didFailToReceiveAdWithError:(NSError *)error
{
if (self.bannerIsVisible)
{
[UIView beginAnimations:@"animateAdBannerOff" context:NULL];
// assumes the banner view is at the top of the screen.
banner.frame = CGRectOffset(banner.frame, 0, -50);
[UIView commitAnimations];
self.bannerIsVisible = NO;
}
}

如果 iAd 接收到广告，当然要恢复显示广告条了，代码

- (void)bannerViewDidLoadAd:(ADBannerView *)banner