IOS基础学习-3: UILabel

UILabel和UIControl一样，是UIView的子类。而UIButton是UIControl的子类，所以某种意义上，UILabel是UIButton的叔类

按照基本功能设置的界面如图。

1. label1:

label1演示了创建label, 字体类型，字体大小，字体颜色，对齐方式，背景色等属性设置；

//label1演示不同的设置属性的方式
    UILabel *label1 = [[UILabel alloc]initWithFrame:CGRectMake(100, 20.0, 200.0, 50.0)];
    //设置显示文字
    label1.text = @"粗体，30号字";
    //设置文字颜色
    label1.textColor = [UIColor orangeColor];
    //设置字体大小
    label1.font=[UIFont systemFontOfSize:30];
    //设置靠右对齐，对齐方式有以下几种：
    label1.textAlignment = NSTextAlignmentRight;
    //设置背景色
    label1.backgroundColor = [UIColor grayColor];

2. label2:

label2演示了不同的字符截取模式。其中本例子中采用了截去中间的方法

//label2演示不同的截取方式
    UILabel *label2 = [[UILabel alloc]initWithFrame:CGRectMake(100, 80.0, 200.0, 50.0)];
    label2.text = txt;
    //enum {
    //NSLineBreakByWordWrapping = 0,
    //NSLineBreakByCharWrapping,
    //NSLineBreakByClipping,
    //NSLineBreakByTruncatingHead,
    //NSLineBreakByTruncatingTail,
    //NSLineBreakByTruncatingMiddle
    //};
    //typedef NSUInteger NSLineBreakMode
    
    label2.lineBreakMode = NSLineBreakByTruncatingMiddle;//截去中间

3. label3:

创建成员变量txt

NSString *txt =  @"白日依山尽，黄河入海流，欲穷千里目，更上一层楼";

创建label3并设置text属性

//label3演示自动换行
    b_SwitchLabel3 = NO;
    label3 = [[UILabel alloc]initWithFrame:CGRectMake(100, 100, 220, 100)];
    label3.text = txt;

用btn0按钮来设置换行

//设置换行
    label3.numberOfLines = 2 ;
    btn0 = [UIButton buttonWithType:UIButtonTypeCustom];
    btn0.frame = CGRectMake(150, 170, 90, 35);
    [btn0 setTitle:@"换行" forState:UIControlStateNormal];
    btn0.backgroundColor = [UIColor grayColor];
    [btn0 addTarget:self action:@selector(switchLabel3:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn0];

btn0对应的方法

//btn0设置label3的换行属性
-(void)switchLabel3:(id)sender {
    UIButton *btnTmp = (UIButton *) sender;
    if(btnTmp == btn0){
        if(b_SwitchLabel3==YES){
            b_SwitchLabel3 = NO;
            label3.numberOfLines  = 1;
            label3.adjustsFontSizeToFitWidth = YES;
            [btn0 setTitle:@"单行" forState:UIControlStateNormal];
        } else{
            b_SwitchLabel3 = YES;
            label3.numberOfLines  = 2;
            label3.adjustsFontSizeToFitWidth = NO;
            [btn0 setTitle:@"两行" forState:UIControlStateNormal];
        }
        
    }
    
}

4. label4:

label4用来演示创建阴影字体。创建阴影字体的关键在于设置shadowColor和shadowOffset属性

//label4演示阴影字体
    UILabel *label4 = [[UILabel alloc]initWithFrame:CGRectMake(100, 200, 200.0, 50.0)];
    label4.text = @"阴影字体";
    label4.shadowColor = [UIColor redColor];
    label4.shadowOffset = CGSizeMake(1.0,1.0);

5. label5:

label5用来演示label的enable和disable属性，这个在系统配置中，能够用来显示哪些配置是可选择的，哪些是不可选择的。

创建label5并设置字体和初始属性

//label5演示enable和disable切换
    label5 = [[UILabel alloc]initWithFrame:CGRectMake(100, 260, 200.0, 50.0)];
    label5.text = @"演示enable/disable";
    label5.font =[UIFont systemFontOfSize:22];
    b_Switch = YES; //设置label4的初始值属性

设置btn1，用来切换label5的enable和disable状态

//设置btn1的属性,btn用来切换label5.enable＝YES/NO;
    btn1 = [UIButton buttonWithType:UIButtonTypeCustom];
    btn1.frame = CGRectMake(150, 300, 90, 35);
    
    btn1.backgroundColor = [UIColor grayColor];
    
    [btn1 setTitle:@"切换" forState:UIControlStateNormal];
    //设置按键字体大小
    btn1.titleLabel.font = [UIFont systemFontOfSize: 20];
    //设置按键字体颜色
    [btn1 setTitleColor:[UIColor blackColor]forState:UIControlStateHighlighted];
    //设置按键目标
    [btn1 addTarget:self action:@selector(switchLabel5:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn1];

btn1对应的方法，其中关键在于设置label5.enable

//btn1设置标签的enable属性
-(void)switchLabel5:(id)sender {
    UIButton *btnTmp = (UIButton *) sender;
    if(btnTmp == btn1){
        if(b_Switch==YES){
            b_Switch = NO;
            label5.enabled = NO;
        } else{
            b_Switch = YES;
            label5.enabled = YES;
        }
        
    }
    
}

6. label6:

演示根据label尺寸，调节字体大小。其中关键属性为adjustsFontSizeToFitWidth

//label6显示字体大小自适应
    label6 = [[UILabel alloc]initWithFrame:CGRectMake(100, 360, 200.0, 50.0)];
    label6.text = @"字体大小可以根据Frame尺寸自适应";
    b_AutoSize=YES;
    label6.adjustsFontSizeToFitWidth = YES;

设置btn2，用来切换自适应开关

btn2.backgroundColor = [UIColor grayColor];
    [btn2 setTitle:@"自适应" forState:UIControlStateNormal];
    //设置按键字体大小
    btn2.titleLabel.font = [UIFont systemFontOfSize: 20];
    //设置按键字体颜色
    [btn2 setTitleColor:[UIColor blackColor]forState:UIControlStateHighlighted];
    //设置按键目标
    [btn2 addTarget:self action:@selector(autoSize:) forControlEvents:UIControlEventTouchUpInside];

btn2对应方法，关键在于设置adjustsFontSizeToFitWidth

//btn2设置标签是否自适应
-(void)autoSize:(id)sender {
    UIButton *btnTmp = (UIButton *) sender;
    if(btnTmp == btn2){
        if(b_AutoSize==YES){
            b_AutoSize = NO;
            label6.adjustsFontSizeToFitWidth = NO;
        } else{
            b_AutoSize = YES;
            label6.adjustsFontSizeToFitWidth = YES;
        }   
    }
}