在iOS中,通常修改UIView.frame中的某一个值是非常痛苦的,因为Size和Origin都是readonly的,所以每次都需要进行如下繁琐的书写:
view.frame = CGRectMake(view.frame.origin.x, 100, view.frame.size.width, view.frame.size.height);
这种写法在UI较多的界面中,写的人非常痛苦,看的人也相当难受(可读性低)。
所以我们需要一个可以直接修改UIView.frame中某一个值的方法,这个方法我们可以给view添加一个category 来实现。
首先我们需要创建一个UIView的category,命名随意,需要在.h中暴露我们想要修改的属性:
#import <UIKit/UIKit.h>
@interface UIView (Layout)
@property (assign, nonatomic) CGPoint origin;
@property (assign, nonatomic) CGFloat x;
@property (assign, nonatomic) CGFloat y;
@property (assign, nonatomic) CGFloat centerX;
@property (assign, nonatomic) CGFloat centerY;
@property (assign, nonatomic) CGSize size;
@property (assign, nonatomic) CGFloat width;
@property (assign, nonatomic) CGFloat height;
@property (assign, nonatomic) CGFloat top;
@property (assign, nonatomic) CGFloat bottom;
@property (assign, nonatomic) CGFloat left;
@property (assign, nonatomic) CGFloat right;
@end
然后在.m文件中手动实现各个属性的setter和getter方法:
#import "UIView+Layout.h"
@implementation UIView (Layout)
/*
@dynamic告诉编译器属性的setter和getter方法都自己实现
*/
@dynamic top;
@dynamic bottom;
@dynamic left;
@dynamic right;
@dynamic origin;
@dynamic x;
@dynamic y;
@dynamic size;
@dynamic width;
@dynamic height;
#pragma mark - top
- (CGFloat)top
{
return self.frame.origin.y;
}
- (void)setTop:(CGFloat)top
{
CGRect frame = self.frame;
frame.origin.y = top;
self.frame = frame;
}
#pragma mark - bottom
- (CGFloat)bottom
{
return self.frame.size.height + self.frame.origin.y;
}
- (void)setBottom:(CGFloat)bottom
{
CGRect frame = self.frame;
frame.origin.y = bottom - frame.size.height;
self.frame = frame;
}
#pragma mark - left
- (CGFloat)left
{
return self.frame.origin.x;
}
- (void)setLeft:(CGFloat)left
{
CGRect frame = self.frame;
frame.origin.x = left;
self.frame = frame;
}
#pragma mark - right
- (CGFloat)right
{
return self.frame.size.width + self.frame.origin.x;
}
- (void)setRight:(CGFloat)right
{
CGRect frame = self.frame;
frame.origin.x = right - frame.size.width;
self.frame = frame;
}
#pragma mark - origin
- (CGPoint)origin
{
return self.frame.origin;
}
- (void)setOrigin:(CGPoint)origin
{
CGRect frame = self.frame;
frame.origin = origin;
self.frame = frame;
}
#pragma mark - x
- (CGFloat)x
{
return self.frame.origin.x;
}
- (void)setX:(CGFloat)value
{
CGRect frame = self.frame;
frame.origin.x = value;
self.frame = frame;
}
#pragma mark - y
- (CGFloat)y
{
return self.frame.origin.y;
}
- (void)setY:(CGFloat)value
{
CGRect frame = self.frame;
frame.origin.y = value;
self.frame = frame;
}
#pragma mark - centerX
- (CGFloat)centerX
{
return self.center.x;
}
- (void)setCenterX:(CGFloat)centerX
{
CGPoint center = self.center;
center.x = centerX;
self.center = center;
}
#pragma mark - centerY
- (CGFloat)centerY
{
return self.center.y;
}
- (void)setCenterY:(CGFloat)centerY
{
CGPoint center = self.center;
center.y = centerY;
self.center = center;
}
#pragma mark - size
- (CGSize)size
{
return self.frame.size;
}
- (void)setSize:(CGSize)size
{
CGRect frame = self.frame;
frame.size = size;
self.frame = frame;
}
#pragma mark - width
- (CGFloat)width
{
return self.frame.size.width;
}
- (void)setWidth:(CGFloat)width
{
CGRect frame = self.frame;
frame.size.width = width;
self.frame = frame;
}
#pragma mark - height
- (CGFloat)height
{
return self.frame.size.height;
}
- (void)setHeight:(CGFloat)height
{
CGRect frame = self.frame;
frame.size.height = height;
self.frame = frame;
}
@end
现在只需要这样就能修改UIView.frame中的任意值:
view.x = 100;
既简洁又方便。