不通过Interface Builder创建更改背景色的范例

Ios代码  
#import <UIKit/UIKit.h>  
  
@interface ColorViewController : UIViewController {  
  UILabel *redValue, *greenValue, *blueValue;  
  UISlider *redSlider, *greenSlider, *blueSlider;  
}  
  
@property(nonatomic, retain) UILabel *redValue;  
@property(nonatomic, retain) UILabel *greenValue;  
@property(nonatomic, retain) UILabel *blueValue;  
@property(nonatomic, retain) UISlider *redSlider;  
@property(nonatomic, retain) UISlider *greenSlider;  
@property(nonatomic, retain) UISlider *blueSlider;  
  
@end  
 
实现文件：
 
Ios代码  
#import "ColorViewController.h"  
  
@implementation ColorViewController  
  
@synthesize redValue, greenValue, blueValue;  
@synthesize redSlider, greenSlider, blueSlider;  
  
- (void)loadView {  
  UIView *contentView = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];  
  [contentView setBackgroundColor:[UIColor blackColor]];  
  self.view = contentView;  
    
  redValue = [[UILabel alloc] initWithFrame:CGRectMake(10, 30, 30, 20)];  
  redValue.text = @"0";  
  redValue.textColor = [UIColor redColor];  
  redValue.backgroundColor = [UIColor blackColor];  
    
  greenValue = [[UILabel alloc] initWithFrame:CGRectMake(10, 90, 30, 20)];  
  greenValue.text = @"0";  
  greenValue.textColor = [UIColor greenColor];  
  greenValue.backgroundColor = [UIColor blackColor];  
    
  blueValue = [[UILabel alloc] initWithFrame:CGRectMake(10, 150, 30, 20)];  
  blueValue.text = @"0";  
  blueValue.textColor = [UIColor blueColor];  
  blueValue.backgroundColor = [UIColor blackColor];  
    
  [self.view addSubview:redValue];  
  [self.view addSubview:greenValue];  
  [self.view addSubview:blueValue];  
      
  [redValue release];  
  [greenValue release];  
  [blueValue release];  
    
  [self.view addSubview:self.redSlider];  
  [self.view addSubview:self.greenSlider];  
  [self.view addSubview:self.blueSlider];  
    
  [contentView release];  
}  
  
- (UISlider *)redSlider{  
  if(redSlider == nil){  
    redSlider = [[UISlider alloc] initWithFrame:CGRectMake(50, 30, 255, 20)];  
    [redSlider addTarget:self action:@selector(changeColor) forControlEvents:UIControlEventValueChanged];  
    redSlider.maximumValue = 255.0;  
    redSlider.minimumValue = 0.0;  
    redSlider.value = 0.0;  
    redSlider.continuous = YES;  
  }  
  return redSlider;  
}  
  
- (UISlider *)greenSlider{  
  if(greenSlider == nil){  
    greenSlider = [[UISlider alloc] initWithFrame:CGRectMake(50, 90, 255, 20)];  
    [greenSlider addTarget:self action:@selector(changeColor) forControlEvents:UIControlEventValueChanged];  
    greenSlider.maximumValue = 255.0;  
    greenSlider.minimumValue = 0.0;  
    greenSlider.value = 0.0;  
    greenSlider.continuous = YES;  
  }  
  return greenSlider;  
}  
  
- (UISlider *)blueSlider{  
  if(blueSlider == nil){  
    blueSlider = [[UISlider alloc] initWithFrame:CGRectMake(50, 150, 255, 20)];  
    [blueSlider addTarget:self action:@selector(changeColor) forControlEvents:UIControlEventValueChanged];  
    blueSlider.maximumValue = 255.0;  
    blueSlider.minimumValue = 0.0;  
    blueSlider.value = 0.0;  
    blueSlider.continuous = YES;  
  }  
  return blueSlider;  
}  
  
- (void)changeColor{  
  NSString *redStr = [[NSString alloc] initWithFormat:@"%d", (int)redSlider.value];  
  NSString *greenStr = [[NSString alloc] initWithFormat:@"%d", (int)greenSlider.value];  
  NSString *blueStr = [[NSString alloc] initWithFormat:@"%d", (int)blueSlider.value];  
  redValue.text = redStr;  
  greenValue.text = greenStr;  
  blueValue.text = blueStr;  
      
  self.view.backgroundColor = [UIColor colorWithRed:[redValue.text floatValue]/255.0 green:[greenValue.text floatValue]/255.0 blue:[blueValue.text floatValue]/255.0 alpha:1.0];   
      
  [redStr release];  
  [greenStr release];  
  [blueStr release];  
}  
  
- (void)dealloc {  
  [super dealloc];  
  [redSlider release];  
  [greenSlider release];  
  [blueSlider release];  
    
  redSlider = nil;  
  greenSlider = nil;  
  blueSlider = nil;  
    
  [redValue release];  
  [greenValue release];  
  [blueValue release];  
      
  redValue = nil;  
  greenValue = nil;  
  blueValue = nil;  
}  
  
@end

 

示例图：