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
iOS开发取随机数肯定会遇到的，暂时小结一下，好像有个arc4random(),所以假如你想取80到100的随机数，就可以写成int randomNumber = arc4random()
+80int index = arc4random() % 6 +1;就是1到6的随机数了。
还有很多其它的取随机数的方法，论坛上也经常讨论
有网友问怎么生成不重复的随机数，说是生成一个随机种子如：
srand(time(NULL));rand() 00;
还有一个这样的函数round(random()+10);取到的是10~24之间的数，但是是个伪随机数
怎么获得0到1之间的随机数，不包括0和1
思路是：求1--100之间的随机数就可以了然后/100
srand(time(0));
(float)(rand() % 100) /100;
(float)(1+arc4random()�)/100
总结：随机数最好使用arc4random，因为使用random()必须手动设置随机种子srandom(time(NULL));否则产生的就是伪随机数。
网友有个这样的想法：
NSArray *temp = [NSArrayarrayWithObjects:@"1",@"2",@"3",@"4", @"5",@"6", nil]; NSMutableArray *tempArray = [[NSMutableArrayalloc]initWithArray:temp]; NSMutableArray*resultArray = [[NSMutableArrayalloc]init]; int i; int count = temp.count; for (i =0; i < count; i ++) { int index =arc4random() % (count - i); [resultArray addObject:[tempArrayobjectAtIndex:index]]; [tempArray removeObjectAtIndex:index]; } [tempArray release]; NSLog(@"resultArray is %@",resultArray);resultArray里面每个object的intValue就是你要的不重复随机数了
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：
NSString *documentsPath = [self getDocumentsDirectory]; NSString *savePath = [documentsPath stringByAppendingPathComponent:@"save.plist"]; if (plistData) { [plistData writeToFile:savePath atomically:YES]; } else { NSLog(errorDesc); [errorDesc release]; }- (NSString *)getDocumentsDirectory { NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); return [paths objectAtIndex:0]; }5 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];
6 读取一般性文档文件
NSString *tmp; NSArray *lines; 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。
7 隐藏NavigationBar
[self.navigationController setNavigationBarHidden:YES animated:YES];
在想隐藏的ViewController中使用就可以了。
