iphone开发nbsp;常用的一些

       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：
        
        
        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];  
        } 
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; 
        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]);
          }

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

///转自：http://www.cocoachina.com/iphonedev/sdk/2009/0626/325.html///