[oc]- < getting started with UI> -- common controls uibutton

UIButton

UIButton Basics

• Buttons are all UI Very important components in the system , stay iOS Middle button UIButton The use of is also very flexible

Create text UIButton

• about UI object We should pay attention to some things when creating , establish UI Is the method of an object a class method or an instance method ？
• establish UI After object , Pay attention to the size , Location Color Wait for details
• Create a UIButton

 UIButton* btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];

Can only be created through class methods buttonWithType

  corner type ：UIButtonTypeRoundedRect

Set up UIButton Properties of

• Set up button Button initialization position

 btn.frame = CGRectMake(100, 100, 100, 40);

• Set button content
  Parameters 1: String type , Display button text
  Parameters 2: Set the text status type ：UIControlStateNormal The normal state

    [btn setTitle:@" Button 1" forState:UIControlStateNormal];

• Display text status type

•  IControlStateHighlighted  Press status 
  

 [btn setTitle:@" Button press status " forState:UIControlStateHighlighted]

• The background color

 btn.backgroundColor = [UIColor grayColor];

• Set the text color
  Parameters 1 Color
  Parameters 2 state

•  UIControlStateNormal  The normal state 
  

[btn setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];

• Press the status color
• Parameters 1 - Color
  Parameters 2 - state UIControlStateHighlighted

 [btn setTitleColor:[UIColor redColor] forState:UIControlStateHighlighted];

• Set font size

btn.titleLabel.font = [UIFont systemFontOfSize:24];

Add to view screen display

• [self.view addSubview:btn];

Without pictures UIButton effect

With pictures UIButton

• For normal applications We can't be buttons like this , Generally speaking, it is with pictures Button The buttons are pleasing to the eye Next, I'll show you how to create a picture Button
• The overall code

-(void) crateImageBtn {
    
    // Create a custom type button
    UIButton* btnImage = [UIButton buttonWithType:UIButtonTypeCustom];

    btnImage.frame = CGRectMake(100, 200, 100, 100);

    UIImage* icon01 = [UIImage imageNamed:@"btn01.jpeg"];
    UIImage* icon02 = [UIImage imageNamed:@"btn02.jpeg"];

    // How to set the button image 
    //p1  display   Picture object 
    //p2  Control state 
    [btnImage setImage:icon01 forState:UIControlStateNormal];
    [btnImage setImage:icon02 forState:UIControlStateHighlighted];

    [self.view addSubview:btnImage];

}

With pictures Button Creation considerations and code interpretation

• Let's customize one first Button
• Our buttons should have two states Press and normal status

  UIControlStateNormal  Ordinary 
  UIControlStateHighlighted  Press down 

• The pictures corresponding to the two states are loaded - Picture name plus format

UIImage* icon01 = [UIImage imageNamed:@"btn01.jpeg"]; UIImage* icon02 = [UIImage imageNamed:@"btn02.jpeg"];

• How to set the button image
• Parameter one ： Show picture objects
• Parameter two ： Control state

[btnImage setImage:icon01 forState:UIControlStateNormal];

 [btnImage setImage:icon02 forState:UIControlStateHighlighted];

effect

• Normal state
  
• Press status

UIButton Event handling

• The so-called event processing is to add the event we want to use when we press the button. When the user clicks the button, the event corresponding to the button will occur So as to achieve the function we want
• Add an event function to the button — One button can add multiple event functions

Multiple parameters of event processing

- Event handler

btn addTarget:(nullable id) action:(nonnull SEL) forControlEvents:(UIControlEvents)

First understand the meaning of parameters

1）
    p1: Who will implement the event function , Who is the object of implementation a、
    addTarget:self  The implementer is himself 
    p2:@selector(pressBtn): Function object , When the button meets p3 When the event type , Call this function 
    p3:UIControlEvent: Event handler type 
   UIControlEventTouchUpOutside： When the finger leaves the screen and the position of the finger is outside the range of the button, the event function will be triggered 
   UIControlEventTouchDown： When our fingers just touch the screen 

Implement event

-(void) createButton {
    
    // Create fillets button
    UIButton *btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    
    btn.frame = CGRectMake(100, 100, 80, 40);
    
    [btn setTitle:@" Button 1" forState:UIControlStateNormal];
    

	
    [btn addTarget:self action:@selector(pressBtn:) forControlEvents:UIControlEventTouchUpInside];
    //UIControlEventTouchUpInside： When the finger leaves the screen and the position of the finger is within the range of the button, the event function will be triggered 
    
    //2） Touch event function 
    [btn addTarget:self action:@selector(touchDown) forControlEvents:UIControlEventTouchDown];
    
    [self.view addSubview:btn];

// The same function can be called by different buttons 
    UIButton *btn2 = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    btn2.frame = CGRectMake(100, 100, 40, 80);
    [btn2 setTitle:@" Button 2" forState:UIControlStateNormal];
    
    [btn2 addTarget:self action:@selector(pressBtn:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn2];
    
    // Set button tag -- I don't know the pointer of the button is written like this 
    btn.tag = 101;
    btn2.tag = 102;

The function that the event needs to call （ One of the parameters ）

// The parameter is the button itself that calls this function -- It is recommended to write like this 
// Benefits are as follows 
-(void) pressBtn:(UIButton*) btn {
    
    if (btn.tag == 101) {
    
        NSLog(@"btn1 pressed");
    } else {
    
        NSLog(@"btn2 pressed");
    }
// NSLog(@"btn pressed");

effect

• Let's first click button one Then the button is touched – Print
• Click button 2 Then I was touched – Print