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

UILabel

UI

UI It's the user interface 
“UI Namely User Interface Written by , That's the user interface .UI Design is user interface design , The interface mainly includes mobile terminal (Android and IOS),PC End ,Dashboard.

UILabel What is it?

 UILabel  Is one that can be displayed on the screen , And can display text UI View 

Create and use a UILabel

• We turn on Xcode choice App Development find ViewController stay Add and create the implementation part UILabel Function of
• 
• Define to create a UILable object
• Display text assignment ,txt It's a string object

    UILabel* label = [[UILabel alloc]init];
   
    // Display text assignment ,txt It's a string object 
    label.text = @"Hello myiOSxxxxxxxxxx";

1）label Primary attribute

• Set up label Display position frame attribute
• CGRectMake(100, 300, 160, 200);
  Note that the first two numbers represent the initial coordinate origin The following numbers represent the downward extension to the right And x y Distance of axis

// Set up label Display position 
    //100x- From the left ,100y From the upper left corner of the edge rectangle  160- wide  40- high 
    label.frame =  CGRectMake(100, 300, 160, 200);

• Set the background color

 label.backgroundColor = [UIColor grayColor];//  There's a background color 
 label.backgroundColor = [UIColor clearColor]; // Transparent color 

• This background color refers to the color of our text display , There will be text color behind
  • Setting of the whole background color

   Setting of the whole background color 
    self.view.backgroundColor = [UIColor whiteColor];

• take label Display on screen -

     take label Display on screen 
    [self.view addSubview:label];

• Set up label Text size
• Set the text color

// Set up label Text size 
    //systemFontOfSize  System default font   size 12
    label.font = [UIFont systemFontOfSize:24];
    
    // Set the text color 
    label.textColor = [UIColor blackColor];

2）label Advanced properties

• Set shadow color

• Set the offset position of the shadow x- Lateral offset , y: Vertical offset downward distance

  CGSizeMake(10, 10);
  

• Set text alignment –textAlignment

• label Number of lines of text display , Default line
  Others are greater than 0 Lines of text Try to show
  If label.numberOfLines = 0,iOS Will automatically calculate the number of lines needed for text , Display as needed

// Set shadow color 
    label.shadowColor = [UIColor blueColor];
    // Set the offset position of the shadow x- Lateral offset , y: Vertical offset downward distance 
    label.shadowOffset = CGSizeMake(10, 10);
    
    // Set text alignment --textAlignment
    //  Default left alignment 
    label.textAlignment = NSTextAlignmentCenter ;
    
    // Set up label Number of lines of text display  , Default line 
    // Others are greater than 0 Lines of text   Try to show 
    // If label.numberOfLines = 0,iOS Will automatically calculate the number of lines needed for text , Display as needed 
    label.numberOfLines = 0 ;

How to see the effect

• open Xcode Select the virtual machine at the top

• 

   Use command+r  function 
  

This is our first UILabel Interface -- We make

  label.numberOfLines = 0 ;

In this way, the system will automatically find the required position according to our purple potato

About a few colors

label.backgroundColor = [UIColor grayColor];//  There's a background color 
label.backgroundColor = [UIColor clearColor]; // Transparent color 
 When we write both of them, the system will default to transparent instead of gray  , So we need to be transparent before writing   Half of it is our own color 

 Setting of the whole background color 
self.view.backgroundColor = [UIColor whiteColor]; The whole background window is white 

 Font and shadow colors 
 label.textColor = [UIColor blackColor];
 label.shadowColor = [UIColor blueColor];
 Pay attention to setting the shadow part   Try not to overlap with the text