- (id)init { self = [super init]; if (self) { //.......... } return self; }
[super init]的返回值和self的类型都是id类型,所以可以这么写。
如果父类初始化失败,会返回nil。所以要判断父类是不是初始化成功了,才能做子类的初始化。因为万一没有初始化成功,相当于对nil操作,会报exception。
触摸屏:
一、首先要在开发板上安装tslib ,具体安装步骤参考我之前的博客:http://blog.csdn.net/start530/article/details/8018096
二、安装完后,加载触摸屏驱动:insmod ts.ko,然后运行./ts_calibrate 进行五点校准,之后会在/etc/下生成一个文件 pointercal,要有这个触摸屏才能用。
三、修改/etc/profile:
添加这几行 :
export QWS_MOUSE_PROTO=Tslib:/dev/input/event0 (这个event*是根据你加载触摸屏驱动后 ls /dev/event* ,然后查看新添加的是哪个event)
export QWS_DISPLAY=LinuxFb:/dev/fb0
export QWS_SIZE=480x272 (通过这个设置qt界面的大小)
保存,退出,在命令行输入 source /etc/profile
四、运行qt可执行程序,ok
界面大小:
在qt main.cpp函数里添加
MainWindow w;
w.resize(480,272); (开发板lcd分辨率)
w.show();
转载请出名出处!
刚开始只是在顶部导航栏添加两个按钮,用来控制主屏的左右移动。
- (void)setupNavBar { _navBar = [[UIView alloc] initWithFrame:CGRectMake(0, 0, self.middleView.frame.size.width, 44)]; self.navBar.backgroundColor = [UIColor blueColor]; [self.middleView addSubview:self.navBar]; UIButton *leftNavBtn = [UIButton buttonWithType:UIButtonTypeRoundedRect]; leftNavBtn.frame = CGRectMake(10, 0, 44, 44); [self.navBar addSubview:leftNavBtn]; [leftNavBtn setTitle:@"Left" forState:UIControlStateNormal]; [leftNavBtn addTarget:self action:@selector(leftNavBtnDidClick:) forControlEvents:UIControlEventTouchUpInside]; UIButton *rightNavBtn = [UIButton buttonWithType:UIButtonTypeRoundedRect]; rightNavBtn.frame = CGRectMake(self.navBar.frame.size.width - 10 - 44, 0, 44, 44); [self.navBar addSubview:rightNavBtn]; [rightNavBtn setTitle:@"Right" forState:UIControlStateNormal]; [rightNavBtn addTarget:self action:@selector(rightNavBtnDidClick:) forControlEvents:UIControlEventTouchUpInside]; }
并且是通过点击按钮修改button的tag来记录当前屏幕展示的状态,有点挫。
后来整理了下,设置一个状态变量:
typedef enum _screenStateType { kNormalState = 0, kLeftState, // Show the left-view kRightState, // Show the right-view kDriftingState // Drifting } ScreenStateType;
通过屏幕状态变量来控制屏幕的左右滑动:
#pragma mark - Slide to Left or Right #define LEFT_SLIDE_OFFSET 260.0f #define RIGHT_SLIDE_OFFSET (-260.0f) - (void)leftNavBtnDidClick:(UIButton *)btn { if (kNormalState == self.screenState) { [self slideFromeState:self.screenState toState:kLeftState]; } else { [self slideFromeState:self.screenState toState:kNormalState]; } } - (void)rightNavBtnDidClick:(UIButton *)btn { if (kNormalState == self.screenState) { [self slideFromeState:self.screenState toState:kRightState]; } else { [self slideFromeState:self.screenState toState:kNormalState]; } } - (void)slideFromeState:(ScreenStateType)oState toState:(ScreenStateType)dState { if (self.isSliding) return ; self.isSliding = YES; __block CGRect rect = self.middleView.frame; rect.origin.x = 0.0f; id completionBlk = nil; switch (oState) { case kNormalState: if (kLeftState == dState) { self.rightView.hidden = YES; rect.origin.x = LEFT_SLIDE_OFFSET; } else if (kRightState == dState) { self.leftView.hidden = YES; rect.origin.x = RIGHT_SLIDE_OFFSET; } break; case kLeftState: case kRightState: if (kNormalState == dState) { completionBlk = ^(BOOL finished) { self.leftView.hidden = NO; self.rightView.hidden = NO; }; } break; case kDriftingState: if (kLeftState == dState) { rect.origin.x = LEFT_SLIDE_OFFSET; } else if (kRightState == dState) { rect.origin.x = RIGHT_SLIDE_OFFSET; } else if (kNormalState == dState) { completionBlk = ^(BOOL finished) { self.leftView.hidden = NO; self.rightView.hidden = NO; }; } break; default: break; } id animationBlk = ^{ self.middleView.frame = rect; }; [UIView animateWithDuration:0.3f animations:animationBlk completion:completionBlk]; self.screenState = dState; self.isSliding = NO; }
当完成这样的功能后,我在模拟器上跑了下,觉得还行。不过在真机跑的时候,我习惯用拇指来滑动,而不是用导航栏的按钮。
当修改为可以通过手指滑屏后,又发现太容易滑了,有点影响用户体验,所以在移动过程先尝试检测下用户是否真的想滑屏:
#pragma mark - Finger Touch - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; CGPoint fingerPoint = [touch locationInView:self.middleView]; if ([self.middleView pointInside:fingerPoint withEvent:nil]) { fingerPoint = [touch locationInView:self.view]; self.lastFingerX = fingerPoint.x; } } - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; CGPoint fingerPoint = [touch locationInView:self.view]; // The user really wants to move the screen ? if (!self.canDrag && abs(fingerPoint.x - self.lastFingerX) > 30) { self.canDrag = YES ; self.lastFingerX = fingerPoint.x; } if (!self.canDrag) return ; CGRect rect = self.middleView.frame; rect.origin.x += (fingerPoint.x - self.lastFingerX); rect.origin.x = (rect.origin.x > LEFT_SLIDE_OFFSET) ? LEFT_SLIDE_OFFSET : rect.origin.x; rect.origin.x = (rect.origin.x < RIGHT_SLIDE_OFFSET) ? RIGHT_SLIDE_OFFSET : rect.origin.x; self.middleView.frame = rect; if (rect.origin.x > 0) { self.rightView.hidden = YES; self.leftView.hidden = NO; } else if (rect.origin.x < 0) { self.leftView.hidden = YES; self.rightView.hidden = NO; } else { self.leftView.hidden = self.rightView.hidden = NO; } self.lastFingerX = fingerPoint.x; } - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { self.canDrag = NO; CGFloat boundary = 50.0f; CGRect rect = self.middleView.frame; ScreenStateType lastScreenState = self.screenState; self.screenState = kDriftingState; switch (lastScreenState) { case kNormalState: if (rect.origin.x < (0 - boundary)) { [self slideFromeState:self.screenState toState:kRightState]; } else if (rect.origin.x > (0 + boundary)) { [self slideFromeState:self.screenState toState:kLeftState]; } else { [self slideFromeState:self.screenState toState:kNormalState]; } break; case kLeftState: if (rect.origin.x < LEFT_SLIDE_OFFSET - boundary) { [self slideFromeState:self.screenState toState:kNormalState]; } else { [self slideFromeState:self.screenState toState:kLeftState]; } break; case kRightState: if (rect.origin.x > RIGHT_SLIDE_OFFSET + boundary) { [self slideFromeState:self.screenState toState:kNormalState]; } else { [self slideFromeState:self.screenState toState:kRightState]; } break; default: [self slideFromeState:self.screenState toState:kNormalState]; break; } }
完整的代码参见:https://gist.github.com/3857426