objective-c

问题 I am a ios developer. I can take a value from arduino sensor. But i cannot send a message by using the following the method. [peripheral writeValue:dataToWrite forCharacteristic:characteristic type:CBCharacteristicWriteWithResponse]; " dataToWrite " value is alloc by using NSString * NSString* data = @"1"; NSData* dataToWrite = [data dataUsingEncoding:NSUTF8StringEncoding]; and the following code is full code of "DiscoverCharacteristics in service" //DISCOVER CHAR -(void)peripheral:

问题 I am a ios developer. I can take a value from arduino sensor. But i cannot send a message by using the following the method. [peripheral writeValue:dataToWrite forCharacteristic:characteristic type:CBCharacteristicWriteWithResponse]; " dataToWrite " value is alloc by using NSString * NSString* data = @"1"; NSData* dataToWrite = [data dataUsingEncoding:NSUTF8StringEncoding]; and the following code is full code of "DiscoverCharacteristics in service" //DISCOVER CHAR -(void)peripheral:

问题 I am a ios developer. I can take a value from arduino sensor. But i cannot send a message by using the following the method. [peripheral writeValue:dataToWrite forCharacteristic:characteristic type:CBCharacteristicWriteWithResponse]; " dataToWrite " value is alloc by using NSString * NSString* data = @"1"; NSData* dataToWrite = [data dataUsingEncoding:NSUTF8StringEncoding]; and the following code is full code of "DiscoverCharacteristics in service" //DISCOVER CHAR -(void)peripheral:

问题 Like many iOS developers, I use CoreData, and like many iOS developers that use CoreData, I have hard-to-track-down thread violation errors. I'm trying to implement a debugging strategy for throwing exceptions when the CoreData concurrency rules are broken. My attempt is below - my question is, is this valid? Will it produce false positives? Summary: when an NSManagedObject is created, note the thread. Whenever a value is accessed later on, check if the current thread is the same as the

问题 in SpriteKit we detect the in the didBeginContact method. but this looks a bit stupid to do something like that: func didBeginContact(contact: SKPhysicsContact) { if let contactA = contact.bodyA.node?.name { if let contactB = contact.bodyB.node?.name { //now that we have safely unwrapped these nodes, we can operate on them if contactA == "ball" { collisionBetweenBall(contact.bodyA.node!, object: contact.bodyB.node!) } else if contactB == "ball" { collisionBetweenBall(contact.bodyB.node!,

问题 in SpriteKit we detect the in the didBeginContact method. but this looks a bit stupid to do something like that: func didBeginContact(contact: SKPhysicsContact) { if let contactA = contact.bodyA.node?.name { if let contactB = contact.bodyB.node?.name { //now that we have safely unwrapped these nodes, we can operate on them if contactA == "ball" { collisionBetweenBall(contact.bodyA.node!, object: contact.bodyB.node!) } else if contactB == "ball" { collisionBetweenBall(contact.bodyB.node!,

问题 in SpriteKit we detect the in the didBeginContact method. but this looks a bit stupid to do something like that: func didBeginContact(contact: SKPhysicsContact) { if let contactA = contact.bodyA.node?.name { if let contactB = contact.bodyB.node?.name { //now that we have safely unwrapped these nodes, we can operate on them if contactA == "ball" { collisionBetweenBall(contact.bodyA.node!, object: contact.bodyB.node!) } else if contactB == "ball" { collisionBetweenBall(contact.bodyB.node!,

问题 in SpriteKit we detect the in the didBeginContact method. but this looks a bit stupid to do something like that: func didBeginContact(contact: SKPhysicsContact) { if let contactA = contact.bodyA.node?.name { if let contactB = contact.bodyB.node?.name { //now that we have safely unwrapped these nodes, we can operate on them if contactA == "ball" { collisionBetweenBall(contact.bodyA.node!, object: contact.bodyB.node!) } else if contactB == "ball" { collisionBetweenBall(contact.bodyB.node!,

问题 After I add a subview to NSView, my mouse events respond to the area of NSView minus the addedSubVIew. How can I avoid that? I want it to respond on all of the superview. Thanks. 回答1: You can also implement the hitTest: method in the container view. - (NSView *) hitTest: (NSPoint) aPoint { return [super hitTest:aPoint] ? self : nil; } Now only the container view can receive the mouse events. 回答2: You can override the subviews [NSView hitTest:] method and return the superview. - (NSView *)

问题 I resume my CABasicAnimation with the following code: CFTimeInterval pausedtime = layer.timeOffset; layer.speed = 1.0; layer.timeOffset = 0.0; layer.beginTime = [layer convertTime:CACurrentMediaTime() toLayer:nil] - pausedTime; which is pretty straightforward. At the very end of this article the author states that with negative speed value animation reverses. I can't understand what timeOffset and beginTime should look like in this case? P.S. I am aware that I can reverse animation by