1.原理
CGRect rect = CGRectMake(10, 20, 150, 30);
// 最小Y坐标,即矩形的顶部top y坐标: minY = rect.y = 20.000000
NSLog(@"CGRectGetMinY = y = %f", CGRectGetMinY(rect));
// 最大Y坐标,即矩形的底部bottom y坐标:maxY = y + height = 50
NSLog(@"CGRectGetMaxY = y + height = %f", CGRectGetMaxY(rect));
// 最小x坐标,即矩形的左边x left坐标 : minX = x = 10
NSLog(@"CGRectGetMinX = x = %f", CGRectGetMinX(rect));
// 最大x坐标,集矩形的右边横坐标right maxX = x + width = 10 + 150 = 160
NSLog(@"CGRectGetMaxX = x + width = %f", CGRectGetMaxX(rect));
// 中点横坐标:midX = x + width/2 = 10 + 150/2 = 10 + 75 = 85
NSLog(@"CGRectGetMidX = x + width/2 = %f", CGRectGetMidX(rect));
// 中点纵坐标:midY = y + height / 2 = 20 + 30/2 = 20 + 15 = 35
NSLog(@"CGRectGetMidY = y + height /2 = %f", CGRectGetMidY(rect));
NSLog(@"CGRectGetWidth = rect.width = %f", CGRectGetWidth(rect)); // width = 150
NSLog(@"CGRectGetHeight = rect.height = %f", CGRectGetHeight(rect)); // height =