frame和bounds

frame其实也是一个结构体，是CGRect的一个变量。

//
//  ViewController.m
//  UIView01
//
//  Created by cqy on 16/2/12.
//  Copyright © 2016年 程清杨. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    //创建View对象
    UIView *view1 = [[UIView alloc]initWithFrame:CGRectMake(20, 20, 200, 100)];
    //设置背景颜色
    view1.backgroundColor = [UIColor yellowColor];
    //添加视图
    [self.view addSubview:view1];
    //frame其实也是一个结构体，有两个成员变量均为结构体，两个成员变量分别有两个成员变量都是cgfloat类型的；
    UIView *view2 = [[UIView alloc]init];
    view2.frame = CGRectMake(20, 140, 200, 100);
    view2.backgroundColor = [UIColor greenColor];

    [self.view addSubview:view2];

    // Do any additional setup after loading the view, typically from a nib.

}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

bounds：在每添加?个view的时候，每个view分别以??的起点为（0，0）点，创建?个坐标系，这个bounds就是?个结构体，?来确定view的新坐标。 

//  ViewController.m
//  UIView01
//
//  Created by cqy on 16/2/12.
//  Copyright © 2016年 程清杨. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    //创建View对象
    UIView *view1 = [[UIView alloc]initWithFrame:CGRectMake(20, 20, 200, 100)];
    //设置背景颜色
    view1.backgroundColor = [UIColor yellowColor];
    //添加视图
    [self.view addSubview:view1];
    //frame其实也是一个结构体，有两个成员变量均为结构体，两个成员变量分别有两个成员变量都是cgfloat类型的；
    UIView *view2 = [[UIView alloc]init];
    view2.frame = CGRectMake(20, 140, 200, 100);
    view2.backgroundColor = [UIColor greenColor];
    [self.view addSubview:view2];
    //bounds也是结构体，与frame一样。只是坐标是从原点开始；
    UIView *view3 = [[UIView alloc]init];
    view3.bounds = CGRectMake(0, 0, 50, 50);
    view3.backgroundColor = [UIColor redColor];
    [view2 addSubview:view3];
    NSLog(@"view1.bounds:%@",NSStringFromCGRect(view1.bounds));//结果：view1.bounds:{{0, 0}, {200, 100}}
    NSLog(@"view1.frame:%@",NSStringFromCGRect(view1.frame));//结果： view1.frame:{{20, 20}, {200, 100}}
    //center是以视图坐标系为参照，取得中点
    UIView *view4 = [[UIView alloc]initWithFrame:CGRectMake(20, 260, 200, 100)];
    view4.backgroundColor = [UIColor brownColor];
    [self.view addSubview:view4];
     NSLog(@"view1.center:%@",NSStringFromCGPoint(view1.center));//结果：view1.center:{120, 70}
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end