转载请注明出处,原文网址:http://blog.csdn.net/m_changgong/article/details/8107957 作者:张燕广
实现的功能:1)不使用xib构建UI,包括一个slider、两个label;2)改变slider的值,label中slider的值随之改变;3)改变slider的值,缩放另一个label中的文本(实际就是改变该label字体的大小)
关键词:slider 缩放 不使用xib
1、创建一个Single View Application工程,命名为:SliderDemo,如下图
2、我们不使用xib构建UI,所以现删除ViewController.xib文件
3、修改ViewController.h后如下:
#import <UIKit/UIKit.h>@interface ViewController : UIViewController//添加代码@property(nonatomic,retain)UILabel *sliderValueLabel;@property(nonatomic,retain)UISlider *slider;@property(nonatomic,retain)UILabel *xLabel;@property(assign,nonatomic)CGFloat initialFontSize;@end
4、修改ViewController.m后如下:
//// ViewController.m// SliderDemo//// Created by Yanguang Zhang on 12-10-24.// Copyright (c) 2012年 __MyCompanyName__. All rights reserved.//#import "ViewController.h"@interface ViewController ()@end@implementation ViewController//添加代码@synthesize slider;@synthesize sliderValueLabel;@synthesize xLabel;@synthesize initialFontSize;//修改代码/*- (void)viewDidLoad{ [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib.}*/-(void)loadView{ UIView *myView = [[UIView alloc]initWithFrame:[UIScreen mainScreen].applicationFrame]; [myView setBackgroundColor:[UIColor whiteColor]]; self.view = myView; //初始化视图 [self initViews];}-(void)initViews{ //初始化slider //sliderValueLabel = [[UILabel alloc]initWithFrame:CGRectMake(20, 30, 50, 40)]; //显示slider值的label sliderValueLabel = [[UILabel alloc]init]; CGRect frame = sliderValueLabel.frame; frame.origin.x = 20; frame.origin.y = 30; frame.size.width = 50; frame.size.height = 40; sliderValueLabel.frame = frame; sliderValueLabel.backgroundColor = [UIColor greenColor]; sliderValueLabel.textAlignment = UITextAlignmentCenter; sliderValueLabel.text = @"0"; //加入到view中 [self.view addSubview:sliderValueLabel]; //slider,通过sliderValueLabel的相对位置定义frame frame.origin.x = CGRectGetMaxX(frame)+10; frame.origin.y = CGRectGetMinY(frame); frame.size.width = 200; frame.size.height = 40; slider = [[UISlider alloc]initWithFrame:frame]; slider.minimumValue = 0;//最小值 slider.maximumValue = 25;//最大值 slider.value = 0;//执行初始值 //设置响应事件(此操作同:使用xib中时将事件与操作IBAction进行关联) [slider addTarget:self //事件委托对象 action:@selector(sliderValueChanged) //处理事件的方法 forControlEvents:UIControlEventValueChanged//具体事件 ]; //加入到view中 [self.view addSubview:slider]; //X label frame.origin.x = 0; frame.origin.y = CGRectGetMaxY(sliderValueLabel.frame)+10; frame.size.width = self.view.frame.size.width; frame.size.height = self.view.frame.size.height-frame.origin.y; xLabel = [[UILabel alloc]initWithFrame:frame]; xLabel.backgroundColor = [UIColor yellowColor]; xLabel.textAlignment = UITextAlignmentCenter; xLabel.text = @"X"; initialFontSize = xLabel.font.pointSize; //NSLog(@"initialFontSize=%.2f",initialFontSize); //加入到View中 [self.view addSubview:xLabel];}//slider值改变时进行处理-(void)sliderValueChanged{ //NSLog(@"sliderValueChanged"); //更新sliderValueLabel的值 sliderValueLabel.text = [[NSString alloc]initWithFormat:@"%.0f",slider.value]; //缩放xLabel的内容 CGFloat newFontSize = initialFontSize*(slider.value+1); //NSLog(@"newFontSize=%.2f",newFontSize); xLabel.font = [xLabel.font fontWithSize:newFontSize];}- (void)viewDidUnload{ [super viewDidUnload]; slider = nil; sliderValueLabel = nil; xLabel = nil; // Release any retained subviews of the main view.}-(void)dealloc{ [super dealloc]; [sliderValueLabel release]; [slider release]; [xLabel release];}- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation{ return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);}@end
5、编译、运行,效果如下
6、总结:xib构建UI方式与写代码方式比较?
1)通过上面代码的编写,仅仅构建一个slider和两个label就很麻烦,不断的修改frame值、调试,才能达到想要的UI效果;并且要alloc很多对象,要控制好内存,防止泄露。可想而知,如果要通过写代码构建一个复杂的UI界面,一定是件很“痛苦”的事儿 。
2)写代码方式也有其优点,比如代码条理比较清晰,出现bug容易定位;用xib的话,构建UI界面比较方便、容易,直接拖动或输入坐标值即可,但是如果控件或事件较多时,N多的连接显得比较乱,而且出现问题不容易查找,尤其连线之后如果再更改IBOulet或IBAction的名称等,更容易出现莫名奇妙的错误。
3)个人感觉,简单的界面尽量用写代码方式,如果界面比较复杂且涉及的事件不太多的话可以用xib实现。见仁见智啦!