在开发中,实时的显示当前的fps能够使我们更加直接的了解app当前的性能及运行状况,代码如下:

FPSLabel.swift

import UIKit

class FPSLabel: UILabel {

fileprivate var displayLink: CADisplayLink?

fileprivate var lastTime: TimeInterval = 0

fileprivate var count: Int = 0

deinit {

displayLink?.invalidate()

}

override func didMoveToSuperview() {

frame = CGRect(x: 15, y: 150, width: 40, height: 40)

layer.cornerRadius = 20

clipsToBounds = true

backgroundColor = UIColor.black

textColor = UIColor.green

textAlignment = .center

font = UIFont.systemFont(ofSize: 24)

run()

}

func run() {

displayLink = CADisplayLink(target: self, selector: #selector(FPSLabel.tick(_:)))

displayLink?.add(to: .current, forMode: .commonModes)

}

@objc func tick(_ displayLink: CADisplayLink) {

if lastTime == 0 {

lastTime = displayLink.timestamp

return

}

count += 1

let timeDelta = displayLink.timestamp - lastTime

if timeDelta < 0.25 {

return

}

lastTime = displayLink.timestamp

let fps: Double = Double(count) / timeDelta

count = 0

text = String(format: "%.0f", fps)

textColor = fps > 50 ? UIColor.green : UIColor.red

}

}

然后在我们的BaseViewController添加如下代码

class BaseViewController: UIViewController {

#if DEBUG

private lazy var newFpsLabel: FPSLabel = {

let label = FPSLabel()

return label

}()

#endif

override func viewDidLoad() {

super.viewDidLoad()

#if DEBUG

view.addSubview(newFpsLabel)

#endif

}

}

OC版代码如下

#import "TJBLFpsLabel.h"

@interface TJBLFpsLabel ()

@property (nonatomic, strong) CADisplayLink *displayLink;

@property (nonatomic, assign) NSTimeInterval lastTime;

@property (nonatomic, assign) int count;

@end

@implementation TJBLFpsLabel

- (void)didMoveToSuperview {

self.frame = CGRectMake(15, 150, 80, 40);

self.layer.cornerRadius = 20;

self.layer.masksToBounds = YES;

self.backgroundColor = [UIColor blackColor];

self.textColor = [UIColor greenColor];

self.textAlignment = NSTextAlignmentCenter;

self.font = [UIFont systemFontOfSize:24];

[self run];

}

- (void)run {

_displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(tick:)];

[_displayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSRunLoopCommonModes];

}

- (void)tick:(CADisplayLink *)sender {

if (_lastTime == 0) {

_lastTime = _displayLink.timestamp;

return;

}

_count += 1;

NSTimeInterval timeDelta = _displayLink.timestamp - _lastTime;

if (timeDelta < 0.25) {

return;

}

_lastTime = _displayLink.timestamp;

double fps = (double)_count / timeDelta;

_count = 0;

self.text = [NSString stringWithFormat:@"%.1f",fps];

self.textColor = fps > 50 ? UIColor.greenColor : UIColor.redColor;

}

@end

添加

#ifdef DEBUG

UIWindow *window = [UIApplication sharedApplication].keyWindow;

TJBLFpsLabel *fpsLabel = [[TJBLFpsLabel alloc] init];

[window addSubview:fpsLabel];

[window bringSubviewToFront:fpsLabel];

#endif

trick函数原理

CADisplayLink 的调用频率始终和屏幕刷新的刷新的频率一致

fps = 刷新次数 / 间隔时间