UILabel的使用、事件响应及传值

创建圆角label，类似输入框的效果，可以这样使用：

UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 60, 30)];
label.backgroundColor = [UIColor blueColor];
// 设置圆角
label.layer.cornerRadius = 10;
[self.view addSubview:label];

UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 200, 36)];
label.layer.borderWidth  = 1.0f;
label.layer.borderColor  = [UIColor darkGrayColor].CGColor;
label.layer.cornerRadius = 5.0f;

UILabel事件响应：

添加一个UILabel，并为label添加了点击事件，怎么才能让事件响应？

UITapGestureRecognizer *tapGestureTel = [[[UITapGestureRecognizeralloc]initWithTarget:self action:@selector(onLabelEvent:)]autorelease];
[myLabel addGestureRecognizer:tapGestureTel];

-(void) onLabelEvent:(UITapGestureRecognizer *)recognizer{
UILabel *label=(UILabel*)recognizer.view;
NSLog(@"%@被点击了",label.text);

}

UILabel 也是一个UIView，同样继承自UIResponder，所以只要扩展UILabel，并覆盖相关方法就可以了，如：

– touchesBegan:withEvent:
– touchesMoved:withEvent:
– touchesEnded:withEvent:
– touchesCancelled:withEvent:

如：

// 点击该label的时候, 来个高亮显示
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[self setTextColor:[UIColor whiteColor]];
}

// 还原label颜色,获取手指离开屏幕时的坐标点, 在label范围内的话就可以触发自定义的操作
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
[self setTextColor:COLOR(59,136,195,1.0)];
UITouch *touch = [touches anyObject];
CGPoint points = [touch locationInView:self];
if (points.x >= self.frame.origin.x && points.y >= self.frame.origin.x && points.x <= self.frame.size.width && points.y <= self.frame.size.height)
{
[delegate myLabel:self touchesWtihTag:self.tag];
}
}

换个思路，既然要加点击事件，为什么不用UIButton，而用UILabel呢？

原因主要是有时通过UIButton无法实现对文字的完美控制，笔者在项目中就遇到这样的情形：当使用粗斜体＋大号字体显示文本时，会有部分文字显示不全。

UILabel添加背景图片

UIColor *color = [UIColor colorWithPatternImage:[UIImage imageNamed:@"itemkaung2.png"]];
[myLabel setBackgroundColor:color];

UILabel如何设置文字居中

label.textAlignment = UITextAlignmentLeft;
label.textAlignment = UITextAlignmentCenter;
label.textAlignment = UITextAlignmentRight;